Question

Q.20 A driver accelerates his car first at the rate of 2.8 m/s2 and then at the rate of 1.4 m/s2.The ratio of two force exerted by the engine in two cases will be?

Answer 1

Given:-

First case:

Acceleration = 2.8 m/s²

Second case:

Acceleration = 1.4 m/s²

[Hint by Imperius: Mass of an object always remains same. Weight varies.]

To Find:-

Ratio of two forces exertee by the Engine in two cases.

Let the mass of the car be = m

We know,

Force = Mass × Acceleration

Case 1:-

Force (F′) = m × 2.8 m/s² = ( 2.8m )m/s²

Case 2:-

Force (F″) = m × 1.4 m/s² = ( 1.4m ) m/s²

Finding ratio of the forces in two cases:-

RATIO:-

$\frac{F″}{F′}$

$= \frac{1.4m \ m/s^2}{2.8m \ m/s^2}$

$= \frac{1.4 m}{2.8 m}$

$= \frac{1}{2} = 1:2$

Therefore, ratio b/w the two cases will be 1 : 2.

@Imperius