Using Machines

Why is the output work always less than the input work for a real machine?

Some of the input work is converted to thermal energy by friction

Find the force needed to lift a 2,000 N weight using a machine with a mechanical advantage of 15.

F(in) = F (out)/MA 133 N

Infer how lubricating a machine affects the output force exerted by the machine.

Friction is a force that opposes the motion of two surfaces sliding past each other. Lubrication a machine increases the output force because it decreases friction.

Explain why in a real machine the output work is always less than the input work.

In a real machine, some of the input work is converted into thermal energy by friction.

The mechanical advantage of a machine is less than one. Compare the distances over which the input and output forces are applied.

The distance over which the output force is applied is greater than the distance that the input force is applied.

Describe the circumstances for which the output work would equal the input work in a machine?

The machine would have to be an ideal machine in which there was no friction.

How does a ramp make lifting an object easier?

Less force is needed to lift an object when using a ramp

Calculate the mechanical advantage of a hammer if the input force is 125 N and the output force is 2,000 N.

MA=F (out)/F (in) MA= 16

Find the efficiency of a machine that does 800 J of work if the input work is 2,400 J.

eff= W (out)/W (in) x 100% 33%