Introduction to Machines

A car jack with a mechanical advantage of 6 needs to produce an output force of 600 N to raise a car. What input force is required? 6 N 100 N 600 N 3,600 N

100N

Yosef applies an input force of 50 N to a crowbar. The crowbar applies a force of 750 N to the lid of a crate. What is the mechanical advantage of the crowbar? The mechanical advantage of the crowbar is________.

15

A bicyclist exerts an input force of 15 N on a bicycle with a mechanical advantage of 12. What is the output force of the bicycle? The output force of the bicycle is _______ N.

180N

Anouk does 150 J of work using a hammer to pull a nail out of a piece of wood, and the hammer does 105 J of work on the nail. What is the efficiency of the hammer? 1.4% 7% 70% 143%

70%

Calculate the efficiency for each machine, then answer the question. Machine A has an input work of 1,000 J and an output work of 250 J. Machine B has an input work of 500 J and an output work of 350 J. Machine C has an input work of 200 J and an output work of 150 J. Which machine is the most efficient? A B C They all have the same efficiency.

C

Select the correct words from the drop-down menus to complete the sentence. The: efficiency input output work :of a machine can never exceed the: efficiency input output work because: force friction mechanical advantage uses some of the work.

output input friction

Mechanical advantage is the ratio of: input force/output force output force/input force input work/output work output work/input work. Efficiency is the ratio of: input force/output force output force/input force input work/output work output work/input work expressed as a percentage.

output force/input force output work/ input work

If a machine has 100% efficiency, it means that output work is equal to input work. output force is equal to input force. output work is twice the input work. output force is twice the input force.

output work is equal to input work.

The efficiency of a machine can be increased by decreasing distance. decreasing force. reducing friction. reducing work.

reducing friction

What does a machine change to make work easier? Select three options. the amount of work done the amount of force applied the time needed to do the work the direction of a force the distance over which a force is applied

the amount of force applied the direction of a force the distance over which a force is applied