Question

A car with mass of 175 kg is moving on horizontal road

with 30 m/s velocity. If the car is accelerated by 5 m/s2

,

then kinetic energy of car after 12 sec will be.

A) 708750 J

B) 875000 J

C) 897570 J

D) 578070 J ​

Answer 1

Answer:

A) 708750 J

Explanation:

According to the given question,

m = mass = 175kg

u = initial velocity = 30 m/s

a = acceleration = 5 m/s^2

t = time = 12 sec

v = final velocity and K.E. = Kinetic energy

And we are asked to find K.E. but we also have to find v to use K.E. formula. As it's asking K.E. after 12 sec , means velocity which is used in the K.E. formula is final velocity.

We know,

• v = u+at

Putting the values we get,

• v = 30+5×12

• v = 30+60

• v = 90 m/s

Now, again

• K.E. = 1/2 ×m×v^2

Putting the values we get,

• K.E. = 1/2× 175 × (90)^2

• K.E. = 708750 J ans.

Thus K.E. of the car after 12 sec with acceleration of 5 m/s^2 , initial velocity 30 m/s and mass 175 kg; is 708750 J.

Answer 2

Given:

Mass, m = 175 Kg

Initial velocity, u = 30m/s

Acceleration, a = 5m/s^2

Time, t = 12 sec

Final velocity, v = ?

Kinetic Energy, KE = ?

Solution:

To find Kinetic Energy (KE)

$\boxed{KE = \dfrac{1}{2}m{v}^{2}}$

To find the value of 'v'

$\boxed{v = u + at}$

v = 30 + 5 × 12

v = 30 + 60

v = 90 m/s

So,

KE = $\dfrac{1}{2} \times 175 \times 90^{2}$

KE = 708750

Therefore, Kinetic Energy of car is 708750 J.

A) 708750 J ✔