Question

kinetic energy of an object of mass 2kg moving with a speed of 3m/s and the potential energy of an object of mass 500g at a height of 20m are respectively (acceleration due to gravity is 10m/s^2)

Answer 1

Answer:

K.E. = 9 J

P.E. = 100 J

Explanation:

Given :

Mass m = 2 kg

Velocity v = 3 m / sec

Now kinetic energy is given as :

= > K.E. = 1 / 2 m v²

= > K.E. = 1 / 2 × 2 × 3² J

= > K.E. = 9 J

Now :

Mass m' =500 g = 0.5 kg

Height h = 20 m

Acceleration due to gravity g = 10 m / sec²

We know potential energy is given as :

= > P.E. = m g h

= > P.E. = 0.5 × 10 × 20 J

= > P.E. = 100 J

Hence we get required answer!

Answer 2

Solving for KE:-

We know, $\boxed{KE = \frac{1}{2} mv^2 }$.

Given that, m = 2 kg and v = 3 m/s.

∴ KE = $\frac{1}{2} (2 kg)(3 m/s)^2$

⇒ KE = $9 kg m/s \times m$

⇒ KE = $9 \ J$.

For PE,

We know, $\boxed{PE_{gravitational}} = mgh$

We are given that, m = 0.5 kg, g = 10 m/s² and h = 20 m.

∴ PE = $(0.5 kg)(10 ms^{-2})(20 m)$

⇒ PE = $5 kgms^{-2} \times 20 m$

⇒ PE = $100 Nm$

⇒ PE = $100 \ J$.

∴ Kinetic energy of an object of mass 2 kg moving with a speed of 3 m/s and the potential energy of an object of mass 500g at a height of 20m are respectively 9 J and 100 J.