# Force Numericals Class 8

Last updated on July 6th, 2023 at 11:03 am

In this post, we will solve a set of **Force Numerical** problems for **class 8** students. In the next section, you will find a set of formulas that are used to solve basic numerical problems of force.

**Formula Used**

F = ma

=> force = mass x acceleration

acceleration = (v-u)/t

acceleration = force/mass

**Force Numericals for Class 8 with solution**

**Question 1) Calculate the force required to change the velocity of an object of mass 4 kg from 2 m s-2 to 4 m s-2 in one second.**

**Solution**:

We will use this force formula, F = ma

mass m = 4 kg

acceleration a = (4-2)/1 m/s

^{2}= 2 m/s^{2}So the force, F = ma = 4 x 2 Newton = 8 N

**Question 2) An object of mass 10 kg is moving with an initial velocity of 2 m s ^{-1}.To make it come to rest in one second, what should be the unbalanced force?**

**Solution:**

mass m = 10 kg.

initial velocity = 2 m s

^{-1}

Velocity at rest = 0 m s^{-1}

time interval = 1 second,

Change in velocity in one second or acceleration = (0-2)/1 m/s^{2}= – 2 m/s^{2}

This negative sign means its retardation.Force = mass x acceleration = 10 x (-2) N = -20 N

The negative sign means the force is acting opposite to the direction of motion.

**Question 3) An object of mass 20 kg is moving with an initial velocity of 2 m s ^{-1}. If its velocity changes to 4 m s^{-1} in one second, what should be the force acting on it? What will be the direction of the motion?**

**Solution**:

Force F = ma

mass m = 20 kg

acceleration a = (4-2)/1 m/s

^{2}= 2 m/s^{2}So the force, F = ma = 20 x 2 Newton = 40 N

The object continues to move in the same direction as the force applied is in the same direction of the motion.

**Practice Problems | Extra numerical questions**

4) A force of 25 Newton is applied on an object of mass 10 kg moving with a velocity of 5 m s^{-1}. If the object gains a velocity of 10 m s^{-1}, calculate the time interval. [Solution]

5) Calculate the force required to change the velocity of an object of mass 8 kg from 4 m s^{-1} to 6 m s^{-1} in 2 seconds. [Solution]

Also check this related post: Force and Laws of Motion class 9 Numericals