1. How much work is required to lift a 4kg object 3m high?
2. When a car stops, 60 000 J of work is done by the brakes
in a time of 6s. Calculate the power of the brakes.
3. A crane lifts a 90 kg mass a height of 12 m. Calculate the
gravitational potential energy gained by the mass. Use
g = 9.8 N/kg.
4. Determine the kinetic energy of a 750-kg roller coaster
car that is moving with a speed of 20.2 m/s.

Moon effect. some people believe that the moon controls their activities. if the moon moves from being directly on the opposite side of earth from you to being directly overhead, by what percentage does (a) the moon's gravitational pull on you increase and (b) your weight (as measured on a scale) decrease? assume that the earth–moon (center-to-center) distance is 3.82 × 10^8 m, earth's radius is 6.37 × 10^6 m, moon's mass is 7.36 × 10^22 kg, and earth's mass is 5.98 × 10^24 kg.

Determine the change in width a, height b, thickness t when a plate is subjected to the uniform distributed load and is made of material having modulus of elasticity e=230 gpa and poisson's ratio ν=1/3. given : a=400 mm and b= 300 mm also the uniformly distributed load in downward y direction of plate is 2 mn/m and in the positive x direction is 3 mn/m and t=20 mm

What is the rate of 12 liters of water moving through a water hose in 4.0 minutes?