A truck driver loads some oil drums into a truck by lifting them directly. Each drum has a mass of 80 kg and the platform of the truck is at a height of 0.8 m above th ground. (a) What force is needed to lift a drum into the truck ?
(b) How much energy is used up in lifting a drum?
(c) After the truck is loaded, the driver drives off. List the major energy changes that take place in moving the truck.
(d) The driver stops the truck at the factory gate. What happens to the kinetic energy of the truck ?
Take g=10 m `s^(-2)`

Explanation

Given ,m=80 kg,h=0.8 m ,g=10 m`s^(-2)`
(a)Force needed to lift a drum
Force of gravity on drum (b)Energy used up in lifting a drum
Gravitational potential energy mgh M
`80xx10xx0.8=640J`
(c )In moving the truck ,the chemical energy of the fuel (diesel) changs into mechanical (kinetic) energy .
(d)On stopping the truck ,the kinetic energy og the truck changes into the heat and sound energies.