Work and Machines Unit Exam

Which of the following statements best describes the relationship between work and energy?

• Work is the rate at which energy is used.

• Work is the energy transferred to or from an object via the application of force along a displacement.

• Energy is the force applied to an object.

• Energy is the distance over which a force is applied.

Which of the following simple machines is used to change the direction of a force?

• Wedge

• Screw

• Pulley

• Wheel and axle

If a lever has an effort arm of 2 meters and a load arm of 0.5 meters, what is its mechanical advantage?

• 0.25

• 1

• 2

• 4

Which of the following is an example of a second-class lever?

• Scissors

• Wheelbarrow

• Fishing rod

• See-saw

Which of the following is NOT a type of simple machine?

• Lever

• Pulley

• Engine

• Inclined Plane

What is the mechanical advantage of a machine that requires an input force of 10 N to lift a 50 N load?

• 0.2

• 5

• 10

• 50

Which class of lever has the fulcrum positioned between the effort and the load?

• First-class lever

• Second-class lever

• Third-class lever

• Fourth-class lever

In a pulley system, if you have a mechanical advantage of 4, how many supporting ropes are there?

• 1

• 2

• 3

• 4

If 100 J of work is done by a machine and it outputs 80 J of useful work, what is the efficiency of the machine?

• 20%

• 50%

• 80%

• 100%

A machine has a mechanical advantage of 3. If the output force is 90 N, what is the input force?

• 30 N

• 45 N

• 60 N

• 90 N