A crane on a building site lifts bricks of total mass 200kg, initially at rest on the ground, with uniform acceleration. When the bricks are 5m from the ground, they have a speed of 5m/s.
How much work is done during this process?
A) 2.5kJ
B) 10kJ
C) 12.5kJ
D) 35kJ

The answer is C: 12.5 KJ

Reason:

Kinetic energy= 1/2 mv^2

= 1/2 x 2000kg x (5m/s)^2

= 2500J

= 2500/1000

= 2.5 KJ

Potential energy= mgh

= 200 x 10 x 5m

= 10,000 J

= 10,000/1000

= 10 KJ

Work done = Energy transferred Kinetic Potential = 10KJ 2.5KJ = 12.5 KJ

potential energy is directly proportional to height.

more height = more potential energy.

greatest increase in height = greatest increase in potential energy

where are the points with the greatest increase in height ?

has to be c-e or d-e .

you cant move and you feel like someones pushing you down onto your bed it can feel like you want to get up but you just can't it can be extremely scary