There is a rock sitting on top of a cliff that is 40 m high. The rock weighs 20 kg. What is the potential energy of the rock?

7840 joules

Explanation:

Given that:

Potential energy of rock = ?

Mass of rock = 20 kg

Height = 40 metres

Acceleration due to gravity g = 9.8m/s2

Recall that potential energy (P.E) is the energy possessed by an object at rest. So, for the rock at rest:

P.E = Mass x Acceleration due to gravity x height

= 20 kg x 9.8m/s2 x 40 metres

= 7840 joules

Thus, the potential energy of the rock is

7840 joules

when it gains or loses electrons

when jerome paddle in flowing river towards east the net speed of jerome will increase

so the net speed of jerome will be given as

now the speed of paul will be same as it is given as he is running on the ground

so

so here we can say since the speed of jerome is more so he will win the race

now as we know the distance so the time difference is given as

so jerome will reach first and the time difference will be 203.55 s or 3.4 min