Problem 1. What is the magnitude of the normal force acting on a stationary object on a horizontal surface? The mass of the object is 5 kg?

Problem 2. An object of mass 500 g is moving along axis x. Its acceleration as a function of time is shown in the figure. Find the net force acting on the object at each moment of time.

Problem 3.Two objects are moving along axis x. The x-components of velocities of the objects as a function of time are shown in the figure. The mass of object 1 is 10 kg and the mass of object 2 is 500 g. Find the direction and the magnitude of the net forces acting on the objects.

Problem 4. A horizontal force of magnitude 20 N is applied to a block of mass 5 kg. The block is on a horizontal surface and it is stationary (it does not move). Find the friction force acting on the block.

Problem 5. A horizontal force of magnitude 10 N is applied to a block of mass 5 kg. The block is on the horizontal surface with the coefficient of static friction 0.3 and coefficient of kinetic friction 0.2. Find the friction force acting on the block.

Problem 6. A horizontal force of magnitude 30 N is applied to a block of mass 5 kg. The block is on the horizontal surface with the coefficient of static friction 0.3 and the coefficient of kinetic friction 0.2. Find the friction force acting on the block.

Problem 7. Find acceleration of an elevator with two passengers if the tension in the rope, attached to the elevator is the same as the tension in the rope attached to an empty stationary elevation of mass 500 kg. The mass of the elevator with two passengers is 650 kg.

Problem 8. A 70 kg passenger is standing on s scale in an elevator. The scale's reading is 1000 N. Find the direction and the magnitude of the elevator acceleration.

Problem 9. An elevator is moving upward with constant acceleration . Find the normal force, acting on a block of mass 5 kg. The block is on the elevator's floor.

Problem 10. Find the horizontal force, which should be applied to a block of mass 10 kg, so that the block is moving with constant acceleration . The block is on the horizontal surface with the coefficient of kinetic friction 0.3.

Problem 11. A horizontal cable pulls a 10 kg block along a horizontal frictionless surface. The tension in the cable is 20 N. How long will it take the block to reach a speed of 5 m/s if the block stars from the rest?

Problem 12. A block of mass 10 kg is traveling a distance of 30 m along a horizontal surface before its stop. The coefficient of kinetic friction between the block and the surface is 0.1 Find initial velocity of the block.

Problem 13. A small block is on a horizontal surface of a large block. What should be an acceleration of the large block so that the small block will slip off the surface of the large block. The coefficient of static friction between the blocks is 0.5. The mass of the small block is 4 kg.

Problem 14. An external force is applied to an object as shown in the figure. The object can move along a horizontal surface. An angle between the direction of the force and horizontal surface is . The mass of the block is 5 kg. The coefficient of kinetic friction between the block and the surface is 0.2.

(a) Find the acceleration of the block if the magnitude of external force is 20 N.

(b) Find the magnitude of external force if the block is moving with constant velocity.

 

 

Problem 15. An external force is applied to a block, which is moving along a vertical surface with constant acceleration. The magnitude of the force is 60 N, the angle between the direction of the force and the vertical surface is (see figure). Find the acceleration of the block if its mass is 5 kg and the coefficient of kinetic friction between the block and the vertical surface is 0.2.

 

 

Problem 16. An object is falling down with constant velocity. Find an air resistance force if the mass of the block is 60 kg.

Problem 17. A block is attached to a rope, which is hanging over a frictionless pulley as shown in the figure. The mass of the block is 10 kg. An external force is applied to the other end of the rope. What is the magnitude of the force if the block is moving up with constant acceleration .

 

 

Problem 18. A box of mass 100 kg is in the back of a truck. The truck is moving with constant acceleration . Find the magnitude of the net normal force acting on the box.