2.3 Mechanical Advantage & Efficiency

Why is mechanical advantage useful?

• To make tasks more difficult
• To reduce the speed of an object
• To decrease the efficiency of a machine
• To output more force with less input force

When choosing which machine will be the most efficient, we want the actual mechanical advantage to be

• equal to 1

• greater than 1

• less than 1

• less than -1

Why are most machines not ideal machines?

• Machines are not ideal due to energy losses, like friction.

• Machines are not ideal due to lack of maintenance.
• Machines are not ideal due to excessive noise.
• Machines are not ideal due to their color.

A force of 745 N is used to push down on a lever. This results in a lifting force of 857 N on a box on the other side of the lever. What is the actual mechanical advantage of the lever?

• 0.87
• 1.25
• 1.42
• 1.15

A force of 385 N is used to push down on a lever. This creates a lifting force of 307 N on the other side of the lever. What is the actual mechanical advantage of the lever?

• 1.532
• 0.245
• 2.113
• 0.7974

The ideal mechanical advantage of a ramp was calculated to be 2.6. Its actual mechanical advantage was calculated to be 1.7. What is its % efficiency?

• 65.38%
• 55.75%
• 78.95%
• 42.31%

A lever with an ideal mechanical advantage of 2.6 has its fulcrum 3.4 m away from a load. How far away from the fulcrum should the effort force be applied?

• 5.2 m

• 6.7 m

• 4.3 m

• 8.84 m