Assignment Chapters 4 and 5

1. An object has these forces applied to it.

a) 15 N [N 20^o E] b) 20 N [N 45^o W] c) 20 N [S]

What is the net force on the object? (4 marks)

2. A boy is pushing a box of mass 3.00 kg along a rough horizontal floor with a force of 45.0 N.

The coefficient of friction between the box and the floor is 0.68. What Is the acceleration of

the box? (4 marks)

3. A crate of mass 6 kg is being pushed with an acceleration of 4 m/s². The coefficient of friction is

0.5. What is the applied force on the crate? (4 marks)

4. A man pushes a 25.0 kg box with a force of 80 N. The frictional force is 42.63 N. With what

force must the man push in order to double the acceleration of the box? (6 marks)

5. A bumper car of mass 200.0 kg, is moving at 10.0 km/h when it hits another bumper car. If it

takes 0.4 s to stop, what is the force of the collision, assuming that the acceleration is uniform?

Express your answer in Newtons. (3 marks)

6. A car Is accelerating southward at 1.5 m/s² on the Great Salt Lake salt flats. A gust of wind from

the west causes a sideways acceleration (90^o to the original motion) of 0.53 m/s². If the car has

a mass of 1700 kg, what is the net force on the car? (4 marks)

7. What is the reaction force for the weight of a hockey player applied to the ice? (1 mark)

8. A man of mass 78 kg is riding in an elevator which is accelerating at a rate of -1.8 m/s². What

is the force of the floor pushing up on the man? (3 marks)

9. An object is attached to the end of a chain, and is being swung in a circle. If the chain broke,

the object would fly off with a linear speed of 5.1 m/s. If the chain has a length of 2.2 m, and

the object has a mass of 8.0 kg,

a) what is the centripetal acceleration of the object? (2 marks)

b) what is the centripetal force on the object? (2 marks)

10. A wheel is rotating with a frequency of 0.26 Hz. What is the radius of motion of a 2.1 X 10^-3g

speck of dirt on the wheel, if the centripetal force on the dirt is 1.8 X 10^-5 N? (2 marks)

11. A bullet is fired from the top of a 150 m tall cliff with a velocity of 500 m/s [20^o below

horizontal]. How far away from the base of the cliff will the bullet land? (4 marks)

12. An artillery gun is fired and the shell has a velocity of 250 m/s [35^o above horizontal]. How

far away is the target that the shell will land on? (4 marks)

13. A 25 kg box has a coefficient of friction of 0.22 with the table it sits on. There is a rope attached

to the box, which runs over a pulley to a second box of mass 20.0 kg. The second box is

hanging from the rope over the edge of the table as shown. What is the acceleration of the

25 kg box? (4 marks)

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November 19, 2013