A stone of mass 2 kg is thrown upwards from the ground with a velocity of 3 m/s. When it reaches maximum height, calculate its potential energy.

Information from the question:-

Mass of the stone = 2 kg

Initial velocity of the stone, u = 3 m/s

To calculate the potential energy, we have to find the maximum height of the object.

Now, the stone is thrown upward that is it is working against gravitational force or gravitational acceleration because gravitational acceleration is always applied downward.

Hence, acceleration, a = -g = 9.8 m/s²

The negative sign indicate that the movement is against the acceleration or the object is deaccelerating or the speed of the object is reducing.

As the motion is against the gravity and when the object reaches the maximum height the final speed of the object will be 0 m/s or we can say the object will not have any velocity when it reaches to the top because the speed of the object is continuously decreasing,

so, the final velocity v = 0 m/s

Now using the equation,

Where, s: distance travelled

u: initial velocity of the object

v: final velocity of the object

a: acceleration of the object

0² = 3² - {2 × (-9.8) × s}

0 = 9 - (-19.6 × s)

0 = 9 + (19.6 × s)

-9 = 19.6 × s

s = -9/19.6

s = -0.45 m

Again, the negative sign indicate that the stone is sent away from the earth.

So, maximum height = 0.45 m

We do not need to include the negative sign further because we only wish to find the maximum height upto which the stone went.

Potential energy = Mass of the object × gravitational acceleration

× distance between the ground and the object

that is , Potential energy = m × g × h

Potential energy = 2 × 9.8 × 0.45

= 8.82 kg m²/s²