You lift a barbell a certain distance from the floor. If you lift it twice as high, its potential energy is (a) twice as great. (b) half as great. (c) the same. (d) none of the above A car moving at...

You lift a barbell a certain distance from the floor. If you lift it twice as high, its potential energy is

(a) twice as great.

(b) half as great.

(c) the same.

(d) none of the above

A car moving at 50 km>h skids 20 m with locked brakes. How far will it skid if its initial speed is 100 km>h?

(a) 60 m

(b) 100 m

(c) 120 m

(d) 180 m