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 the 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 2
Answers
Answer:
(i) F = mg = 80 x 10 = 800N.
(ii) Energy = m x g x h = 80 x 10 x 0.8 = 640J.
(iii) In this case F = mg sinθ = 800 x 0.8/3 = 640/3 = 213.3N
It is less than the answer in part (i) as the efforts acts through 3 m whereas the weight is lifted up through 0.8 m. The effort needed may be 300 N instead of 213.3 N owing to loss of energy in overcoming friction and air resistance.
(iv) The energy released owing to combustion of fuel changes into kinetic energy of the truck and load, and this changes in heat energy of the pebbles on the road and of wheels.
(v) The kinetic energy is dissipated as heat.
Explanation:
hope it's helpful
ANSWERS
(i) F = mg = 80 x 10 = 800N.
(ii) Energy = m x g x h = 80 x 10 x 0.8 = 640J.
(iii) In this case F = mg sinθ = 800 x 0.8/3 = 640/3 = 213.3N
It is less than the answer in part (i) as the efforts acts through 3 m whereas the weight is lifted up through 0.8 m. The effort needed may be 300 N instead of 213.3 N owing to loss of energy in overcoming friction and air resistance.
(iv) The energy released owing to combustion of fuel changes into kinetic energy of the truck and load, and this changes in heat energy of the pebbles on the road and of wheels.
(v) The kinetic energy is dissipated as heat.