Name:________________________________________ Date:______________________ Period:_______
Honors Physics
Mechanical Advantage and Efficiency Practice
1. John exerts a force of 186N on a lever to raise a 2700N object to a height of 29cm. If the efficiency of the
lever is 53.3%, how far does john move his end of the lever?
2. Aaron uses a pulley system to raise a 23.1kg block to a height of 14.0m. If a force of 124N is exerted and
the rope is pulled 34.2m, find the efficiency of the system.
3. A levers efficiency is 92.4%. There is 108J put into the system. How much work did the user get out?
4. A wheel and axle with an ideal mechanical advantage of 5.0 is 67% effiecient. WHat is the mechanical
advantage of the wheel and axle?
5. A seesaw is a lever. Suppose you use a seesaw to lift a bucket of sand. What is the ideal mechanical
advantage of the seesaw if the efficiency of the seesaw is 72%, the effort force is 36N, and the resistance
force is 144N?
6. Alex uses a lever that has a mechanical advantage of 6.5 to lift a 250N object. With how much force
does Alex have to push in order to raise this object using this machine?
7. Eric wants to get his 400N couch into his 5th floor apartment. In order to do so he sets up a pulley
system that has an efficiency of 65%. If Eric 5th floor apartment is 35m off the ground, and when using the
pulley Eric needs to pull his end of the rope for 85m, with what force does Eric need to pull?
8. A wooden board is set up like a ramp. The raised end of the board is 1.0 meters above the ground. A
300N crate is pushed up[ the board fo a distance of 5.0m with an 80N force.
a. Draw a picture of this problem. Label the effort force, effort distance, resistance force and resistance
distance.
b. What is the work input? What is the work output?
c. What is the mechanical advantage of the machine? What is the ideal mechanical advantage of the
machine?
d. What is the efficiency of the machine? Why is the efficiency below 100%? Where did the energy
go?
9. What does it mean for a machine to have a mechanical advantage of 3.0?
You get 3 times more force out than you put in