Which statement best describes why a machine is useful?
A machine does a greater amount of work than the amount of work that is done on it.
O Amachine does a smaller amount of work than the amount of work that is done on it.
A machine can decrease both the input force and the input distance needed to do a given amount of work.
Amachine can decrease either the input force or the input distance needed to do a given amount of work.

According to newtons universal law of gravitation, which would change the parh of the ball so it traces out widest curved path possible?

Aperson stands on a platform, initially at rest, that can rotate freely without friction. the moment of inertia of the person plus the platform is ip. the person holds a spinning bicycle wheel with its axis horizontal. the wheel has moment of inertia iw and angular velocity ωw. take the ωw direction counterclockwise when viewed from above. part a what will be the angular velocity ωp of the platform if the person moves the axis of the wheel so that it points vertically upward?

An object moves from position +34m to the position -15m in 15 seconds. what is the total displacement? what is the total velocity?