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If you push a object w/ 2xs the force and 2xs the distance, how much does work increase?
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4xs
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Which requires more work: lifting a 50kg sack vertically 2m or lifting a 25kg sack up 4m vertically?
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both require the same amount of work
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A ball is thrown straight upward at 20m/s. Ideally, (no air resistance) the ball will return in the thrower's hand at what speed?
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20m/s
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vector
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a quantity that has magnititude and direction
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When bullets are fired from an airplane in the forward direction, what will happen to the momentum of the airplane?
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it will decrease
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An object is dropped and falls freely to the ground with an acceleration of a 1 g. What is its acceleration if its thrown upward at angle?
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still gravity - 9.8 m/s/s
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what is a projectile?
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a moving object
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What is the resultant of a 4-unit and 3-unit vector at right angles to each other
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5 ( think multiples when dealing with 3-4-5 triangles)
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Energy is changed from one form to another with no loss or gain. What is this stament?
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Always true.
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Jose can jump vertically 1 m on his skateboard when it was at rest. How far can Jose jump?
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1 m
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give one unit of speed
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k/h
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Which has more mass, a kg of feathers or a kg of nails
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they are both the same
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At what part of the path does a projectile have minimum speed?
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the top of its path
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if you lift two loads up one story, how much work do you do compared to lifting one load up one story?
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2xs the work
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How much force is needed to keep a cannon fired into frictionless space going?
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0
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An object tavels 2 meters in the 1st second of travel, 2 meters again in the 2nd second of travel and 2 meters in the 3rd second of travel. What is the acceleration
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0
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Does the vertical velocity change the horizontal velocity?
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no
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What is the average speed of a car going 100 kilometers in two hours
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50 km/h
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When there is no air resistance, a ball would go the farthest if thrown at this angle
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45 degrees
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If you drop a faether and a coin at the same time in a vacuum tube, which will reach the bottom first?
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both will fall at the same time
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Ten second after starting from resta car is movingat 40 m/h. What is the car's average acceleration?
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4m/s/s
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At the instant a ball is thrown horizontally with a large force an identical ball is dropped from the same height. which the ball hits the ground first?
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both fall at the same time
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An arrow in a bow has 70 J of PE.assuming no loss of energy due to heat, how much kinetic energy will it have after it has been shot?
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70 J
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The hang time for most athletes are about?
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less than one second
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what are the components of a vector?
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magnitude and d9irection
------->
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What is the minimum resultant possible when adding 3N and 8N?
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5N
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units of power
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watts
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If a ball is thrown in the air at some angle. What will the ball's velocity be at the top of its path?
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changing
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A rifle with a muzzle velocity of 100m/s is fired from a tower. Neglecting air resistence, where will the bullet be 1 s later?
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100 m
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What is friction?
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a force that acts as a force of touching objects
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A rifle with a muzzle velocity of 100 m/s is fired horizontally from a tower. Neglecting air resistance, where will the bullet be in 10 seconds?
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1000 m
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A projectile is fired horizontally in a vacuum. Whay does the projectile maintain its horizontal component speed?
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because of Newton's 1st law
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Equilibrium occurs when?
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when the net forces equal 0
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If a free falling object were somehow equiped with a sppedometer, its speed would increase by __ m/s
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9.8
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If a an object weighs 10 kg on the earth then what does it weigh on the moon?
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10 kg
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A ball is thrown straight up. Its instaneous speed at the top of its path is what?
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0 (but its velocity is not)
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A ball is thrown sraight up its acceleration is what?
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9.8 m/s b/c of velocity
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Suppose an object is in free fall. Each second the object falls a ________ distance than the second before
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farther
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A sheet of paper can be withdrawn from under a container if milk without toppling it if the paper is jerked quickly. Why can this be done?
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because of inertia
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The weight of a person can be represented by a vector that acts in what direction?
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downward
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In the abscence of air resistance, an object falls at a constant what?
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acceleration
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The force required to keep maintain an object at a constant speed in free space is equal to__.
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0
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Consider drops falling from a water faucet. When the drops fall they fall _________ than before
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farther
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scalar
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quantity that has magnitude
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speed
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d/t
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when you look at the speedometer in a moving car, you can seethe car's ...
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instanteous speed
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If an object has linear kinetic energy then it must be what?
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moving
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A cannonball is fired at some angle into the air. In the 1st second it moves 10 meters horizontally. Assuming it doesn't hit the ground and air resistance is small, how far does it move in the next second?
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10 m
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What is the resultant of a 4-unit and 3-unit vector at right angles to each other
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5 ( think multiples when dealing with 3-4-5 triangles)
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If you lift one load up 2 stories how much work do you do compared to lifting it up only one story?
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2xs the work
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force x distance
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work
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Does the vertical velocity change the horizontal velocity?
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no
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what must an object with kinetic energy have?
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momentum
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the energy due to position
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Potential energy
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What does the law of inertia state?
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it resists change to its state of motion (an object is lazy)
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What is the maximum resultant when adding a 3N force to a 8N force?
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11N
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What does the law of inertia apply to?
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objects in motion or at rest
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1/2mv/v
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kinetic energy
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Which has a greater kinetic energy, a car traveling at 30 km/h or a half as massive car traveling at 60km/h?
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60km/h
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A 10 N force and a 30 N foce act in the same direction. what is the net force?
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40 N
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If one object has twice as much mass as another object, then the object also has twice the __________.
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momenum
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A 10-N force and a 30-N force act on an object in different directions. What is the net force of the object?
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20-N
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What approximates the best resultant of a pair of 10-unit vectors at right angles to each other?
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14-units
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how much does a kg of nails weigh?
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9.8 N
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A job is done slowly and an identical job is done quickly. Both jobs require the same amounts of work but different amounts of what?
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power
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a rock that is thrown straight up reaches the top of its path and is starting to fall back down. what is its acceleration?
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9.8 m/s/s
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Suppose a car is moving in a straight lineand steadily increases its speed. It moves from 35 km/h to 40 km/h and from 40 km/ h the next second. What is the acceleration?
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5km/h
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when an object falls freely from acceleration, what increases?
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its velocity
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Why will a ball never go as far as physics ideally predicts?
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because of friction
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If the force of gravity suddenly stopped acting on the planets, what woul happen?
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it continues in a straight line
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At the instant a ball is thrown horizontally with a large force, an identical ball is dropped from the same height. Which ball hits the ground 1st?
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they both hit at the same time
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A person on a roof throws one ball downward and an identical ball upward at the same speed. the ball thrown downward hits the ground with 100 J of KE. Ignoring air friction, with how much kinetic energy does the second ball hit the ground?
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100 J
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In the abscence of air fricton, does a vertical component of a projectile's velocity change as the projectile moves?
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no, it does not
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What is the resultant of a 4-unit and 3-unit vector at right angles to each other
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5 ( think multiples when dealing with 3-4-5 triangles)
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A woman can lift barrels a vertical distance of 1 m or can roll them up a 2 m long ramp at the same elevation. Which one will require 1/2 the force?
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the 2m ramp
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a horizontal component of a projectile is independent of the ....
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vertical component
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hypothesis
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an educated guess
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An object weighs 30N on earth. A 2nd object weighs 30N on the moon.Which has the greater mass?
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30-N on the moon
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How much farther will a car at 100 km/h skid than the same car at 50 km/h
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4xs as much
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The mass of a dog that weighs 100 N weighs how much in kgs?
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10
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If you push a car on the earth and as hard as you push it on the moon. why is this?
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b/c of inertia
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An object following a straight-line path at constant speed has__ _______ _______ __ __
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no forces acting on it.
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A car accelerates at 5 m/s/s. Assuming the car starts from rest , how much time would it take to accelerate the car to 30 m/s/s?
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6s
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what is a theory
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it is observation that has not been proven wrong yet
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A ball is thrown into the air with 100 J of kinetic energy which is transformed to gravitational potential energy at the top of its trajectory. When it returns to its original level after encountering air resistance, what is its kinetic energy?
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the same- 100J
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If a ball rolls down one plane how far will it go up another?
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to its initial point
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You would have to travel to what planet to have the largest force if it only weighs 1-N on Earth?
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Pluto
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unit of work
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joules
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A bullet fired horizontally hits the ground in 0.5 seconds. If it had been fired with a much greater speed in the same direction, it would have hit the ground when?(neglecting the earth's curvature and air restistance)
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0.5 seconds
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a car accelerates at 2 m/s/s. Assuming the car starts from rest., how much time does does it take to accelerate to s speed of 30m/s
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15 s
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If a woman stands on a scale w/ 2 feet and weighs 500-N, how much will she weigh if she lifts one foot?
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500-N
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physics is the most basic science because...
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it is about the world around us
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Friction is a force that always acts in what direction?
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the opposite direction
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work/time
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power
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A ball tossed vertically upwards, reahes its highest point and then falls back to its starting point.During this time,the acceleration is always in what direction?
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downward
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