The work of gravity going UP hill is POSITIVE NEGATIVE NEED

The work of gravity going UP hill is; POSITIVE NEGATIVE NEED MORE INFO The work of drag friction going UP hill is; POSITIVE NEGATIVE NEED MORE INFO The work of a spring as its compressed is; POSITIVE NEGATIVE NEED MORE INFO What is the CHANGE IN ENERGY when a 3 lbs object goes from 75 miles/hour to 40 miles/hour?

Solution

A. Gravity force is downward and body moves upward. So, work done is negative.

B. Body moving upward is accompanied with opposite friction. So, work is negative.

C. Work of as pring when compressed is potential energy which is positive.

D. Change in energy = 0.5(3)(75^(2) - 40^(2)) = 6037.5 lb-miles^(2) per hour^(2)