pointsAll 1.2/2 Submissions NotesQuestion: Walker4 4.P.004.
Starting from rest, a car accelerates at 1.8 m/s up a hill that is inclined 5.5 above the horizontal. How far horizontally and vertically has the car traveled in 11 s? horizontally vertically 108 10.4 m m
2
2.2/2 pointsAll Submissions NotesQuestion: Walker4 4.P.015.
Playing shortstop, you pick up a ground ball and throw it to second base. The ball is thrown horizontally, with a speed of 26 m/s, directly toward point A. When the ball reaches the second baseman 0.50 s later, it is caught at point B. (Neglect air resistance.)
(a) How far were you from the second baseman? 13 m
(b) What is the distance of vertical drop, AB? 1.225 m
3.3/3 pointsAll Submissions NotesQuestion: Walker4 4.P.025.
A ball rolls off a table and falls 0.67 m to the floor, landing with a speed of 5.4 m/s. (a) What is the acceleration of the ball just before it strikes the ground? 9.8 m/s
2
(b) What was the initial speed of the ball?
4.0
m/s
(c) What initial speed must the ball have if it is to land with a speed of 6.1 m/s? 4.9 m/s
4.2/2 pointsAll Submissions NotesQuestion: Walker4 4.P.029.
A second baseman tosses the ball to the first baseman, who catches it at the same level from which it was thrown. The throw is made with an initial speed of 21.0 m/s at an angle of 35.0 above the horizontal. (Neglect air resistance.) (a) What is the horizontal component of the ball's velocity just before it is caught? 17.2 m/s
(b) How long is the ball in the air? 2.45 s
5.1/1 pointsAll Submissions NotesQuestion: Walker4 4.P.034.
In a game of basketball, a forward makes a bounce pass to the center. The ball is thrown with an initial speed of 4.1 m/s at an angle of 14.5 above the horizontal. It is released 0.84 m above the floor. What horizontal distance does the ball cover before bouncing? 2.11 m
6.1/1 pointsAll Submissions NotesQuestion: Walker4 4.P.044.
A certain projectile is launched with an initial speed v0. At its highest point its speed is v0/2. What was the launch angle? 60
7.1/1 pointsAll Submissions NotesQuestion: Walker4 4.P.046.
A dolphin jumps with an initial velocity of 12.0 m/s at an angle
of 36.0 above the horizontal. The dolphin passes through the center of a hoop before returning to the water. If the dolphin is moving horizontally when it goes through the hoop, how high above the water is the center of the hoop? 2.54 m
8.3/3 pointsAll Submissions NotesQuestion: Walker4 4.P.062.
A hummingbird is flying in such a way that it is initially moving vertically with a speed of 5.5 m/s and accelerating horizontally at 11.5 m/s . Assume the bird's acceleration remains constant for the time interval of interest.
2
(a) Find the x component of the hummingbird's velocity at the time t = 0.50 s. 5.75 m/s
(b) Find the y component of the hummingbird's velocity at the time t = 0.50 s. 5.5 m/s
(c) What is the bird's direction of travel at this time relative to the positive x axis?.
43.7
9.2/2 pointsAll Submissions NotesQuestion: Walker4 4.P.068.
When the dried up seed pod of a scotch broom plant bursts open, it shoots out a seed with an initial velocity of 3.0 m/s at an angle of 60.0 above the horizontal.
(a) If the seed pod is 1.1 m above the ground, how long does it take for the seed to land? (Neglect air resistance.) .807 s
(b) What horizontal distance does it cover during its flight? 1.21 m
10.1/1 pointsAll Submissions NotesQuestion: Walker4 4.P.072.
A ball thrown straight upward returns to its original level in 2.00 s. A second ball is thrown at an angle of 32.0 above the horizontal. What is the initial speed of the second ball if it also returns to its original level in 2 s? 18.5 m/s
11.1/1 pointsAll Submissions NotesQuestion: Walker4 5.P.003.
In a grocery store, you push a 13.5 kg shopping cart with a force of 10.5 N. If the cart starts at rest, how far does it move in 2.50 s?
2.43
m
12.1/1 pointsAll Submissions NotesQuestion: Walker4 5.P.004.
You are pulling your little sister on her sled across an icy (frictionless) surface. When you exert a constant horizontal force of 101 N, the sled has an acceleration of 1.9 m/s If the sled has a mass of 8.2 kg, what is the mass of your little sister? 45 kg
2
13.2/2 pointsAll Submissions NotesQuestion: Walker4 5.P.012.
A 747 jetliner lands and begins to slow to a stop as it moves along the runway. The mass is 3.9 10 kg, its speed is 28.2 m/s, and the net braking force is 4.23 10 N. (a) What is its speed 7.49 s later? 20 m/s
5 5
(b) How far has it traveled in this time? 181 m
14.3/3 pointsAll Submissions NotesQuestion: Walker4 5.P.018.
On vacation, your 1300 kg car pulls a 540 kg trailer away from a stop light with an acceleration of 2.05 m/s . (a) What is the net force exerted on the trailer? 1.1 kN
2
(b) What force does the trailer exert on the car? 1.1 kN
(c) What is the net force acting on the car? 2.67 kN
15.2/2 pointsAll Submissions NotesQuestion: Walker4 5.P.020.
As shown in the figure, a force of magnitude 7.50 N pushes three boxes with masses m1 = 1.30 kg, m2 = 2.90 kg, and m3 = 5.00 kg.
(a) Find the magnitude of the contact force between boxes 1 and 2. 6.44 N
(b) Find the magnitude of the contact force between boxes 2 and 3. 4.08 N
16.3/3 pointsAll Submissions NotesQuestion: Walker4 5.P.022.
Two boxes sit sidebyside on a smooth horizontal surface. The lighter box has a mass of 5.35 kg, the heavier box has a mass of 7.55 kg. (a) Find the contact force between these boxes when a horizontal force of 5.0 N is applied to the light box. 2.93 N
(b) If the 5.0 N force is applied to the heavy box instead, is the contact force between the boxes the same as, greater than, or less than the contact force in part (a)? less than
(c) Verify your answer to part (b) by calculating the contact force in this case. 2.07 N
17.1/1 pointsAll Submissions NotesQuestion: Walker4 5.P.061.
At the local grocery store, you push a 13.0kg shopping cart. You stop for a
moment to add a bag of dog food to your cart. With a force of 12.0 N, you now accelerate the cart from rest through a distance of 2.05 m in 3.00 s. What was the mass of the dog food? 13.3 kg
1.1/1 pointsAll Submissions NotesQuestion: Walker4 5.P.025.
A farm tractor tows a 3735 kg trailer up a 14.9 incline at a steady speed of 2.0 m/s. What force does the tractor exert on the trailer? (Ignore friction.) 9.42 kN
2.1/1 pointsAll Submissions NotesQuestion: Walker4 5.P.027.
A shopper pushes a 7.5 kg shopping cart up a 13 incline, as shown in the figure. Find the magnitude of the horizontal force, F, needed to give the cart an acceleration of 1.21 m/s . 26 N
2
3.1/1 pointsAll Submissions NotesQuestion: Walker4 5.P.028.
Two crewmen pull a boat through a lock, as shown in the figure. One crewman pulls with a force of F1 = 135 N at an angle of = 34 relative to the forward direction of the raft. The second crewman, on the opposite side of the lock, pulls at an angle of 45. what With force F2 should the second crewman pull so that the net force of the two crewmen is in the forward
direction? 107 N
4.4/4 pointsAll Submissions NotesQuestion: Walker4 5.P.032.
A 55 kg skier speeds down a trail, as shown in the figure. The surface is smooth and inclined at an angle of = 21 with the horizontal.
(a) Find the direction and magnitude of the net force acting on the skier. Magnitude 193 N Direction
perpendicular from the slope (into the ground) perpendicular from the slope (away from ground) uphill, parallel to slope towards the center of the earth away from the center of the earth downhill, parallel to slope (b) Does the net force exerted on the skier increase, decrease, or stay the same as the slope becomes steeper? decrease increase stay the same
5.2/2 pointsAll Submissions NotesQuestion: Walker4 5.P.041.
When you weigh yourself on good old terra firma (solid ground), your weight is 155 lb. In an elevator your apparent weight is 106 lb. What are the direction and magnitude of the elevator's acceleration? Direction Magnitude downward 3.1 m/s
2
6.1/1 pointsAll Submissions NotesQuestion: Walker4 5.P.044.
A 23 kg suitcase is being pulled with a constant speed by a handle that is at an angle of 21 above the horizontal. If the normal force exerted on the suitcase is 195 N, what is the force F applied to the handle? 85.4 N
7.1/1 pointsAll Submissions NotesQuestion: Walker4 5.P.051.
An ant walks slowly away from the top of a bowling ball, as shown in the figure. If the ant starts to slip when the normal force on its feet drops below oneninth its weight, at what angle does slipping begin? 83.6
8.2/2 pointsAll Submissions NotesQuestion: Walker4 5.P.070.
Your groceries are in a bag with paper handles. The handles will tear off if a force greater than 43 N is applied to them. (a) What is the greatest mass of groceries that can be lifted safely with this bag, given that the bag is raised with constant speed? 4.4 kg
2
(b) What if it is raised with an acceleration of 1.47 m/s ? 3.81 kg
9.1/1 pointsAll Submissions NotesQuestion: Walker4 6.P.003.
A baseball player slides into third base with an initial speed of 8.10 m/s. If the coefficient of kinetic friction between the player and the ground is 0.35, how far does the player slide before coming to rest? 9.56 m
10.2/2 pointsAll Submissions NotesQuestion: Walker4 6.P.006.
When you push a 1.50 kg book resting on a tabletop it takes 2.35 N to start the book sliding. Once it is sliding, however, it takes only 1.50 N to keep the book moving with constant speed. What are the coefficients of static and kinetic friction between the book and the tabletop? static .16
kinetic
.10
11.1/1 pointsAll Submissions NotesQuestion: Walker4 6.P.010.
To move a large crate across a rough floor, you push on it with a force F at an angle of 21 below the horizontal, as shown in the figure. Find the force necessary to start the crate moving, given that the mass of the crate is m = 35 kg and the coefficient of static friction between the crate and the floor is 0.50. 224 N
12.2/2 pointsAll Submissions NotesQuestion: Walker4 6.P.014.
A person places a cup of coffee on the roof of her car while she dashes back into the house for a forgotten item. When she returns to the car, she hops in and takes off with the coffee cup still on the roof. (a) If the coefficient of static friction between the coffee cup and the roof of the car is 0.27, what is the maximum acceleration the car can have without causing the cup to slide? Ignore the effects of air resistance. 2.65 m/s
2
(b) What is the smallest amount of time in which the person can accelerate the car from rest to 17 m/s and still keep the coffee cup on the roof?
6.42
s
13.1/1 pointsAll Submissions NotesQuestion: Walker4 6.P.022.
A 108 kg box is loaded into the trunk of a car. If the height of the car's bumper decreases by 11 cm, what is the force constant of its rear suspension? 9.6 kN/m
14.3/3 pointsAll Submissions NotesQuestion: Walker4 6.P.032.
The pulley system in the figure is used to lift a crate of mass m = 61kg. Note that a chain connects the upper pulley to the ceiling and a second chain connects the lower pulley to the crate. Assume that the masses of the chains, pulleys, and ropes are negligible.
(a) Determine the force required to lift the crate with constant speed. 300 600 N N (b) Determine the tension in the upper chain.
(c) Determine the tension in the lower chain. 600 N
15.2/2 pointsAll Submissions NotesQuestion: Walker4 6.P.035.
In the figure we see two blocks connected by a string and tied to a wall, with = 29. The mass of the lower block is m = 1.0 kg; the mass of the upper block is 2.0 kg.
(a) Find the tension in the string connecting the two blocks. 4.8 N
(b) Find the tension in the string that is tied to the wall. 14 N
16.2/2 pointsAll Submissions NotesQuestion: Walker4 6.P.041.
To immobilize a fractured femur (the thigh bone), doctors often utilize the Russell traction system illustrated in the figure. Notice that one force is applied directly to the knee,
3 1
, while two other forces,
2
and
3
, are
2
applied to the foot. The latter two forces combine to give a force knee experiences the total force traction system is to have
total total
+
that is transmitted through the lower leg to the knee. The result is that the =
1
+
2
+
3
. The goal of this
directly in line with the fractured femur, at an
angle of 20.0 above the horizontal.
Find the following if m = 4.61 kg. (a) The angle required to produce this alignment of 60
total total
.
(b) The magnitude of the force, case. 115 N
, that is applied to the femur in this
17.2/2 pointsAll Submissions NotesQuestion: Walker4 6.P.047.
Find the tension in each of the strings in the figure, given that m1 = 0.6 kg, m2 = 2.2 kg, and m3 = 3.1 kg. Assume the table is frictionless and the masses move freely.
(a) (b)
string between m1 and m2 3.1 14.4 N N string between m2 and m3
18.1/1 pointsAll Submissions NotesQuestion: Walker4 6.P.056.
Find the linear speed that the bottom of a test tube must have in a centrifuge if the centripetal acceleration there is to be 51430 times the acceleration of gravity. The distance from the axis of rotation to the bottom of the test tube is 6.3cm. .178 km/s
19.2/2 pointsAll Submissions NotesQuestion: Walker4 6.P.064.
You swing a 5.1kg bucket of water in a vertical circle of radius 1.4 m. (a) What speed must the bucket have if it is to complete the circle without spilling any water? 3.71 m/s
(b) How does your answer depend on the mass of the bucket? the speed is independent of the mass
20.1/1 pointsAll Submissions NotesQuestion: Walker4 6.P.097.
As your plane circles an airport, it moves in a horizontal circle of radius 1800 m with a speed of 355 km/h. If the lift of the airplane's wings is perpendicular to the wings, at what angle should the plane be banked so that it doesn't tend to slip sideways? 29