A 0.50 kg block initially at rest on a frictionless horizontal surface is acted upon by a force of 8.0 N for a distance of 7.5 m. What is the velocity of the block in m/s?

Answer 1

If the movement is in the direction of the force,

KEblock=workputin
1/2 m v^2=8N*7.5m
solve for v

Answer 2

A 150-L water heater is rated at 8 kW. If 20 percent of its heat escapes, how long does the heater take to raise the temperature of 150 L of water from 10 oC to 60 oC?