Chapter 20 Test Review 7 th Grade

1 How does a ramp make lifting a heavy object easier? A. the object is moved over a short distance. B. the ramp increases the amount of work that you do. C. Less force is needed to move the object over a longer distance. D. More force is needed to move the object over a longer distance.

Answer Less force is needed to move an object over a longer distance.

2 Which of the following causes machines not to be 100% efficient? a.Friction b.Input force c.Output force d.power

Answer friction

3 Which of the following is a compound machine? a.first-class lever b.Block and tackle pulley c.Wheel and axle d.screw

Answer Block and tackle pulley

4 Which of the following would increase the mechanical advantage of a first-class lever? a.Applying a greater input force. b.Increasing the rate at which a force is applied. c.Decreasing the load d.Moving the fulcrum closer to the load

Answer Moving the fulcrum closer to the load

5 The greater the ratio of an inclined plane’s length to it’s height, the greater the a.Mechanical efficiency b.Mechanical advantage c.Work d.power

Answer Mechanical advantage

THINGS TO KNOW Terms: machine, power, work output, work input, mechanical efficiency, mechanical advantage, force, work,energy, compound machine, three classes of levers, three types of pulleys Create a formula card. There is one short answer and one extra credit that must be answered in complete sentences.