# Acceleration Numericals Class 9

In this post, we will solve a set of numerical problems based on the acceleration formula and related concepts (for class 9 students).

**Formulas Used**

1) Acceleration = change in velocity/duration of time

2) Acceleration = force/mass

**Acceleration Numericals for class 9**

**1 ) A car is moving with a velocity of 30 m/s. The driver accelerated it for 5 seconds and reached a velocity of 40 m/s. What is the acceleration?**

Solution:Initial velocity = 30 m/s and final velocity is 40 m/s.

And the elapsed time = 5 seconds

Therefore, accelerationa= change in velocity/elapsed time =(40 -30) / 5m/s^{2}=2 m/s^{2}

Acceleration is2 m/s[Answer]^{2}

**2 ) A car is moving with a velocity of 30 m/s. The driver applied brake for 3 seconds to bring it down to zero. What is the value of acceleration? Is it retardation?**

Solution:Initial velocity =30 m/s and final velocity is 0 m/s.

And the elapsed time = 3 seconds

Therefore, accelerationa= change in velocity/elapsed time =(0-30) / 3m/s^{2}=-10 m/s^{2}

So, acceleration =-10 m/s^{2}

The negative value ofatells that it’s actually retardation.

**3 )** An automobile manufacturer decides to build a car that can accelerate uniformly from 0 to 27 m/s in 10 s. The car’s mass is to be about 1,000 kilograms. What is the force required?

Solution:First, we must determine the acceleration and then use Newton’s second law to find the force.

acceleration a = change in velocity/elapsed time = (27-0)/10m/s= 2.7 m/s^{2}^{2}

So the force needed to cause this acceleration is:

F = ma = 1,000 x 2.7 N = 2,700 N

**4 )** A 10 N force is applied on an object of 10 kg. What will be the acceleration of the object?

Solution:

Given, Force F =10 N

Mass = m = 10 kg

So, acceleration a = F/m = 10/10 **m/s ^{2}** = 1

**m/s**

^{2}Acceleration= 1

**m/s**(Answer)

^{2}