Arock resting high in a cliff is an example of an object with what type of energy?
kinetic energy because it is doing work
kinetic energy because it has the ability to do work
potential energy because it is doing work
potential energy because it has the ability to do work

If the work required to stretch a spring 3 ft beyond its natural length is 15 ft-lb, how much work is needed to stretch it 27 in. beyond its natural length?

Scientific models are based on current knowledge, which can limit their effectiveness when new discoveries are made.

In which situation is the acceleration of a car negative? question 5 options: a)the velocity of a car was 75 km/hr over 4 hours. b)the velocity of a car reduced from 50 km/hr over one minute. c)the velocity of a car increased from 40 km.h to 75 km/h over 15 minutes. d)the velocity of a car was 45 km/hr at 2: 00pm and at 4: 00pm its velocity was 85 km/ht.