Question

A 500kg car which was initially at rest travelled with an acceleration of 5m seconds it's kinetic energy after 4 seconds was

Answer 1

Answer:

Explanation:

Given,

Mass, m = 500 kg

Acceleration, a = 5 m/s²

Time taken, t = 4 Seconds.

To Find,

Kinetic energy

Formula to be used,

1st equation of motion, v = u + at

Kinetic energy = 1/2 × mv²

Solution,

By putting all the values, we get

v = u + at

⇒ v = 0 + 5 × 4

⇒ v = 20 m/s²

Here, the acceleration is 20 m/s².

Now, Kinetic energy,

K.E = 1/2 × mv²

⇒ K.E = 1/2 × 500 × (20)²

⇒ K.E = 1/2 × 500 × 400

⇒ K.E = 1/2 × 200000

⇒ K.E = 100000

⇒ K.E = 100 KJ

Hence, the kinetic energy is 100 KJ.

Answer 2

Given :-

Mass = 500 kg

Time = 4 sec

Acceleration = 5 m/s²

To Find :-

Kinetic energy

Solution :-

We know that

v = u + at

v = 0 + (5)(4)

v = 0 + 20

v = 20 m/s

Now

KE = 1/2 mv²

KE = 1/2 × 5000 × (20)²

KE = 1/2 × 5000 × 400

KE = 2500 × 4000

KE = 100000 J

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