An object, subject to several forces, is moving to the right at constant velocity.

1. An object, subject to several forces, is moving to the right at constant velocity. The vector arrows in the figure below represent the forces on the object. Which of the following force diagrams is correct?

2. The object below is subject to several forces. Which of the vector arrows below represent the direction of the acceleration of the object?

3. The thrust force of a rocket remains approximately constant until the fuel is totally exhausted. While the engine is firing, does the rocket’s acceleration (a) increase (b) decrease (d) remain the same?

4. The gravitational force between two objects of mass m1 and m2 , separated by a distance r, is given by The weight of a person of mass m on the Earth’s surface is given by W = mg What would the weight of the person be at a height of REabove the Earth’s surface, where RE is the radius of the Earth? (a) mg (b) 2mg (c) mg/2 (d) mg/4 (e) zero

5. The weight of a body of mass m near the Earth’s surface can be expressed by W=mg. The gravitational force between two objects of mass m1 and m2 , separated by a distance r, is given by If the mass of the Earth is ME and its radius is RE, which of the following is the correct expression for g? a) b) c) d) None of the above

6. If the earth had the same mass but twice its radius your weight at its surface relative to your present weight, be: a) the same because your mass has not changed b) twice as large c) half as larger d) 4 times as large e) 1/4 as larger

7. On the moon, would your weight (as measured on a bathroom scale) be ? a) greater then on earth b) less than on earth c) the same as on the earth Why?

8. T T 1 T 2 T 1 2 T 3 T 3 T T 1 2 T 3 A 5.0 kg ball is suspended by light cords as sketched on the right. Which free body diagram of point P is most correct? a) b) e) None of the above c) d)

9. For the frictionless pulley system on the right, is the force F needed to hold the block at a given height a) greater than mg b) less than mg c) equal to mg Hint: draw a FBD for each object.

10. Ignoring the mass of the rope in the pulley system at right, is the force F required to hold the block at a given height a) greater than mg b) equal to mg c) equal to 2mg d) equal to mg/2 e) greater than 2mg Hint: draw a FBD for each object.