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1.

A box of mass 23 kg is at rest on a horizontal frictionless surface. A constant horizontal force of magnitude F then acts on the box, accelerating it to the right. You observe that it takes the box 7.5 seconds to travel 38 meters. What is the magnitude of the force F?

2.

A 10-kg object is hanging by a very light wire in an elevator that is traveling upward. The tension in the rope is measured to be 75 N. What are the magnitude and direction of the acceleration of the elevator?

3.

A box of mass 72 kg is at rest on a horizontal frictionless surface. A constant horizontal force of magnitude F then acts on the box, accelerating it to the right. You observe that it takes the box 3.4 seconds to travel 13 meters. What is the magnitude of the force F?

4.

During a hard stop, a car and its passengers slow down with an acceleration of 8.0 m/s². What magnitude force does a 50-kg passenger exert on the seat belt in such a stop?

5.

A 958-N rocket is coming in for a vertical landing. It starts with a downward speed of 25 m/s and must reduce its speed to 0 m/s in 8.0 s for the final landing. (a) During this landing maneuver, what must be the thrust due to the rocket's engines? (b) What must be the direction of the engine thrust force?

6.

A 590-kg rocket is at rest on the launch pad. What upward thrust force is needed to accelerate the rocket uniformly to an upward speed of 28 m/s in 3.3 s?

7.

A catcher stops a 0.15-kg ball traveling at 40 m/s in a distance of 20 cm. What is the magnitude of the average force that the ball exerts against his glove?

8.

In a certain particle accelerator, a proton reaches an acceleration of 9.0 10¹³ m/s². The mass of a proton is 1.67 10^-27 kg. What is the force on the proton?

9.

A 40-kg crate is being lowered with a downward acceleration is 2.0 m/s² by means of a rope. (a) What is the magnitude of the force exerted by the rope on the crate? (b) What would be the magnitude of the force exerted by the rope if the crate were being raised with an acceleration of 2.0 m/s²?

10.

A flatbed truck is carrying an 800-kg load of timber that is not tied down. The maximum friction force between the truck bed and the load is 2400 N. What is the greatest acceleration that the truck can have without losing its load?

11.

A catcher stops a 0.15-kg ball traveling at 40 m/s in a distance of 20 cm. What is the magnitude of the average force that the ball exerts against his glove?

12.

A 590-kg rocket is at rest on the launch pad. What upward thrust force is needed to accelerate the rocket uniformly to an upward speed of 28 m/s in 3.3 s?

13.

A 958-N rocket is coming in for a vertical landing. It starts with a downward speed of 25 m/s and must reduce its speed to 0 m/s in 8.0 s for the final landing. (a) During this landing maneuver, what must be the thrust due to the rocket's engines? (b) What must be the direction of the engine thrust force?

14.

. A 5.0-kg block and a 4.0-kg block are connected by a 0.6 kg rod, as shown in the gure. The links between the blocks and the rod are denoted by A and B. A vertical upward force of magnitude F is applied to the upper block. The blocks and rod assembly are moving downward at constant velocity of 85 cm/s. (a) What is the magnitude of the applied force F? (b) What magnitude force does link A exert? A 5.0-kg block and a 4.0-kg block are connected by a 0.6 kg rod, as shown in the gure. The links between the blocks and the rod are denoted by A and B. A vertical upward force of magnitude F of magnitude 150 N is applied to the upper block. What magnitude force does each of the links A and B exert? Three blocks, light connecting ropes, and a light frictionless pulley comprise a system, as shown in the figure. An external force of magnitude P is applied downward on block A, causing block A to accelerate downward at a constant 2.5 m/s. The tension in the rope connecting block B and block C is equal to 60 N. (a) What is the magnitude of the force P? (b) What is the mass of block C? a=2.5 m/s2 18 kg B A 12 kg 60 N C PThe gure shows a system consisting of three blocks, a light frictionless pulley, and light connecting ropes that act horizontally 0n the upper two blocks. The 9.0kg block is on a perfectly smooth horizontal table. The surfaces of the 12-kg block are rough, with W = 0.30 between the 12kg and 9.0kg blocks. The mass M of the hanging block is set so that it descends at a constant velocity of 3.25 m/s. (a) What is the mass M ofthe hanging block? (b) The mass M is now changed to 5.0 kg, causing it to accelerate downward after it is released. What is the acceleration of the hanging mass? -"9 As shown in the figure, block B on a horizontal tabletop is attached by very light horizontal strings to two hanging blocks, A and C. The pulleys are ideal, and the coefficient of kinetic friction between block B and the tabletop is 0.100. The masses of the three blocks are mA = 12.0 kg, mg = 7.00 kg, and mc = 10.0 kg. Find the magnitude and direction of the acceleration of block B after the system is gently released and has begun to move. B A C