Question

calcute the potential energy of an object of mass 50 kg raised to a height of 4 m above the ground. If the object falls down, what is the kinectic energy when it has fallen through 2 m. take g = 9.8 ms^-2​

Answer 1

•=

=50 =4 =9.8 /2

=50×9.8×4

=1960

=1/2 ^2

Answer 2

Question:-

Calcute the potential energy of an object of mass 50 kg raised to a height of 4 m above the ground. If the object falls down, what is the kinectic energy when it has fallen through 2 m. Take g = 9.8 ms^-2

Solution:-

P.E = mgh

P.E = 50 × 4 × 9.8

P.E = 200 × 9.8

P.E = 1960 J.

Now,

u = 0

v = ?

a = 9.8

s = 2

where u means initial velocity;

v means final velocity and

a mean acceleration due to gravity and

s means height/distance.

$v {}^{2} = 2 \times 9.8 \times 4$

$\Longrightarrow \: v {}^{2} = 19.6 \times 4 \\ \\ \Longrightarrow \: v = \sqrt{19.6 \times 2} \\ \\\Longrightarrow v = 2.8 \: \frac{m}{s}$

Now, Kinetic energy = 1/2 mv^2.

$= \frac{1}{2} \times 50 \times (2.8) {}^{2}$

= 196 J.

Thus, kinetic energy when it has fallen through 2 m is 196 J.