Question

A driver decreases the speed of a car from 25m/s to 10m/s in 5 seconds.find the acceleration of the car??​

Answer 1

Question :

A driver decreases the speed of a car from 25m/s to 10m/s in 5 seconds.find the acceleration of the car?

Answer :

Initial velocity of car, u = 25m/s

Final velocity of car, v = 10m/s

Time taken, t = 5 s

$formula \: to \: find \: acceleration \: \\ a = \frac{v - u}{t} \\ a = \frac{10 - 25}{5} \\ a = \frac{ - 15}{5} \\ a = - 3m \: per \: s {}^{2}$

Thus, the acceleration of car is, -3m/s^2. The negative sign of acceleration means that is retardation. So, we can also say that the car has retardation of +3m/s^2.

Answer 2

Given:

A driver decreases the speed of a car from 25m/s to 10m/s in 5 seconds.

To find:

Acceleration of car ?

Calculation:

• Acceleration is a vector quantity characterized by the rate of change of velocity with respect to time.

Applying EQUATIONS OF KINEMATICS:

$\rm \: v = u + at$

$\rm \implies \: 10 = 25 + a(5)$

$\rm \implies \: 5a = 10 - 25$

$\rm \implies \: 5a = - 15$

$\rm \implies \: a = - 3 \: m {s}^{ - 2}$

So, acceleration of car is 3 m/s²

• Negative sign denotes that the car is regarding or slowing down.