Energy, Work & Simple Machines

A force of 12 N is used to lift a box 0.5 meters above a floor. What amount of work was done to lift the box?

• 6.0 N/m  
• 11.5 N
• 12.5 N 
• 24.0 N/m

How much work is done in moving the cart?  

• 20J  
• 500J 
• 1000 J
• 2000 J

How much power is required to lift a 2.0 kg object 5 meters in 4.50 seconds?  

• 0.45 Watts  
• 2.22 Watts
• 21.8 Watts
• 45.0 Watts 

The efficiency of a machine is always less than 100 percent because

• a machine cannot have an IMA greater than 1. 
• some work input is lost to friction.
• the work input is too small.
• the work output is too great.

If you know the input distance and output distance of a machine, which of the following can you calculate?

• work
• efficiency
• actual mechanical advantage
•  ideal mechanical advantage

An inclined plane reduces the effort force by

• increasing the distance through which the force is applied.
• increasing the work.
• reducing the effort distance.
• reducing the work.

The ideal mechanical advantage of a pulley system is equal to the

• distance the load has to move.
• length of the rope.
• number of rope  segments supporting the load.  
• weight of the object being lifted.

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

• screw 
• wedge 
• lever
• handle

What does the power of a machine measure?  

• The rate of doing work.
• The strength of the machine. 
• The force the machine produces. 
• The total amount of work completed.

Which class of lever best describes the machine shown:

• 1st Class 
• 2nd Class
• 3rd Class 
• 4th Class