Question

A stone of mass 0.5kg strikes the ground with a velocity of 40 m/s. How much is the kinetic energy of the stone at the time it strikes the ground?​

Answer 1

Answer:

ANSWER

Given : h=40 m m=2kg u=0m/s

Force due to air resistance f=20N

Acceleration of the stone a=g−

m

f

=10−

2

20

=0 m/s

2

Using v

2

−u

2

=2aS

∴ v

2

−0=2(0)×40 ⟹v=0m/s

Answer 2

Answer:

Explanation:

Given :

• Mass of a stone (m) = 0.5 kg
• Velocity (v) = 40 m/s

To Find :

• The kinetic energy of the stone at the time it strikes the ground.

Formula to be used :

• Kinetic energy formula,,ie,, K.E = 1/2 × mv^2.

Solution :

★ Kinetic energy,

K.E = 1/2 × mv^2

⟶ K.E = 1/2 × 0.5 × (40)^2

⟶ K.E = 0.25 × 1600

⟶ K.E = 400 J

Hence, the kinetic energy of the stone at the time it strikes the ground is 400 J.

Know to more :

• Potential energy formula, ie,, P.E = mgh
• Mechanical energy formula, ie,, M.E = P.E + K.E