The gravitational potential energy:
E p = m x g x h
where m is the mass and h is the height;
m = 50 kg, g = 9.81 m/s² , h = 40 m
E p = 50 kg x 9.81 m/s² x 40 m
Answer:
E p = 19,620 J = 19.62 kJ
Explanation:
Let the speeds of father and son are
. The kinetic energies of father and son are
. The mass of father and son are 
(a) According to given conditions, 
And 
Kinetic energy of father is given by :
.............(1)
Kinetic energy of son is given by :
...........(2)
From equation (1), (2) we get :
..............(3)
If the speed of father is speed up by 1.5 m/s, so the ratio of kinetic energies is given by :


Using equation (3) in above equation, we get :

(b) Put the value of
in equation (3) as :

Hence, this is the required solution.
BALANCED FORCES
When two forces acting on an object are equal in size but act in opposite directions, we say that they are balanced forces . a stationary object stays still. ... a moving object continues to move at the same speed and in the same direction.
- <em>BRAINLIEST answerer</em>
Answer:
Final speed of the car, v = 24.49 m/s
Explanation:
It is given that,
Initial velocity of the car, u = 0
Acceleration, 
Time taken, t = 7.9 s
We need to find the final velocity of the car. Let it is given by v. It can be calculated using first equation of motion as :

v = 24.49 m/s
So, the final speed of the car is 24.49 m/s. Hence, this is the required solution.