Answer to Question #217309 in Classical Mechanics for Help

Question

True or False. When non-conservative forces are present, the amount of work done increases with the length of the path.

Use the information below the answer the following 3 questions.

A 50 kg crate is being dragged across a floor by a force of 225 N at an angle of 40^o from the horizontal. The crate is dragged a distance of 5.0 m and the frictional force is 60 N.

1) The work done on the crate by the applied force is ___x10² Nm.

2) The work done on the crate by the frictional force is -___x10² Nm.

3) The net work done on the crate is ___x10² Nm.

Do not use rounded answers in subsequent calculations!

Answer 1

$\text{A-priory:}$

$\text{A non-conservative force is one for which work done on the object}$

$\text{depends on the path taken by the object.}$

$\text{Answer: True}$

$W = Fs \cos\alpha$

$W = 225*5*\cos40\degree=8.62*10^2$

$W_{fr}=-F_{fr}s$

$W_{fr}=-F_{fr}s= 60*5= 3*10^2$

$W_{clear}= (F\cos\alpha -F_{fr})s$

$W_{clear}= (225\cos40\degree -60)*5=5.62*10^2$

$\text{Answer:}$

1) The work done on the crate by the applied force is 8.62x10² Nm.

2) The work done on the crate by the frictional force is -3x10² Nm.

3) The net work done on the crate is 5.62x10² Nm.