Question

A stone of mass 750g is thrown vertically upwards with a velocity of 10m/s. Calculate the potential energy at the greatest height.

Answer 1

Answer:

37.485J (joules)

Explanation:

Given:

mass(m) = 750g = (750/1000)kg = 3/4 kg

initial velocity(u) = 10m/s

At greatest height(s), the velocity of the body will be 0

=> final velocity(v) = 0m/s

Potential energy(P.E) = m*gravitational acceleration(g)*s

We need to find the value of height(s) so that we have the value of every variable in the P. E formula.

According to the third equation of motion;

v^2 - u^2 = 2*acceleration(a)*s

a = g in this case as acceleration produced is due to acceleration due to gravity on the body.

=> a = -9.8 m/s^2 minus as the ball is thrown vertically upwards so acceleration is in the opposite direction of that of gravity.

=> 0 - (10)^2 = 2*(-9.8)*s

=> -100 = 2*( -19.6)*s

=> s = 5.10m

Now,

P.E = (3/4)*(9.8)*(5.10)

=> P.E = (149.94)/(4)

= 37.485J

Hence,

P.E at greatest height reached by the body is 37.485J