Question

A body of mass 2 kg is thrown vertically upwards with an initial velocity of 20 m/s. What will be
its potential energy at the end of 2 s? (Assume g = 10 m/s²)
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Answer 1

A body of mass 2 kg is thrown vertically upwards with an initial velocity of 20 m/s.

We have to find the potential energy at the end of 2 sec.

From above data we have; mass (m) is 2 kg, time (t) is 2 sec, initial velocity (u) is 20 m/s.

Also, acceleration due to gravity (a) = -10 m/s ('a' is taken as negative because it is acting in the opposite direction as that of motion)

Using the Second Equation Of Motion

s = ut + 1/2at²

Substitute the values in the above formula,

→ s = 20(2) + 1/2 × (-10)(2)²

→ s = 40 - 20

→ s = 20

Therefore, the distance covered by the body is 20 m.

Now,

Potential Energy (P.E.) = mgh

Substitute the values,

→ 2 × 10 × 20

→ 400 J

Therefore, the value of potential energy is 400 J.