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Unit_3_Problem_Set

# Unit_3_Problem_Set - Unit 3 Problem Set 3.1 A 6.0-kg object...

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Unit 3 Problem Set 3.1 A 6.0-kg object undergoes an acceleration of 2.0 m/s 2 . (a) What is the magnitude of the resultant force acting on it? (b) If this same force is applied to a 4.0-kg object, what acceleration is produced? 3.2 A football punter accelerates a football from rest to a speed of 10 m/s during the time in which his toe is in contact with the ball (about 0.20 s). If the football has a mass of 0.50 kg, what average force does the punter exert on the ball? 3.3 A 5.0-g bullet leaves the muzzle of a rifle with a speed of 320 m/s. What total force (assumed constant) is exerted on the bullet while it is traveling down the 0.82-m-long barrel of the rifle? 3.4 A performer in a circus is fired from a cannon as a “human cannonball” and leaves the cannon with a speed of 18.0 m/s. The performer’s mass is 80.0 kg. The cannon barrel is 9.20 m long. Find the average net force exerted on the performer while he is being accelerated inside the cannon. 3.5 Find the tension in each cable supporting the 600-N cat burglar in Figure P4.15. 3.6 Find the tension in the two wires that support the 100-N light fixture in Figure P4.16. 3.7 Two people are pulling a boat through the water as in Figure P4.20. Each exerts a force of 600 N directed at a 30.0° angle relative to the forward motion of the boat. If the boat moves with constant velocity, find the resistive force F exerted by the water on the boat.

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3.8 The distance between two telephone poles is 50.0 m. When a 1.00-kg bird lands on the telephone wire midway between the poles, the wire sags 0.200 m. Draw a free-body diagram of the bird. How much tension does the bird produce in the wire? Ignore the weight of the wire. 3.9 A 1000-N crate is being pushed across a level floor at a constant speed by a force F of 300 N at an angle of 20.0° below the horizontal as shown in Figure P4.37a. (a) What is the coefficient of kinetic friction between the crate and the floor? (b) If the 300-N force is instead pulling the block at an angle of 20.0° above the horizontal as shown in Figure P4.37b, what will be the acceleration of the crate? Assume that the coefficient of friction is the same as found in (a). 3.10 A hockey puck is hit on a frozen lake and starts moving with a speed of 12.0 m/s. Five seconds later, its speed is 6.00 m/s. (a) What is its average acceleration? (b) What is the average value of the coefficient of kinetic friction between puck and ice? (c) How far does the puck travel during this 5.00-s interval? 3.11 A box of books weighing 300 N is shoved across the floor of an apartment by a force of 400 N exerted downward at an angle of 35.2° below the horizontal. If the coefficient of kinetic friction between box and floor is 0.570, how long does it take to move the box 4.00 m, starting from rest?
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