Question

A body is moving with a speed of 1 m/s and a
constant force F is needed to stop it in a distance
x. If the speed of the body is 3 m/s the force
needed to stop it in the same distance x will be
(121.5 F
(2) 3F
(3)6 F
(4)9F​

Answer 1

Answer:

9F

Explanation:

Stopping distance is given as

• x = u²/(2a)

Acceleration (a) from Newton's second law is given as

• a = F/m

So,

• x = u²/(2F/m)
• F = u²m/(2x)

From above relation, for a body of mass "m" with constant stopping distance "x",

• F ∝ u²

F₂/F₁ = (u₂/u₁)²

F₂ = F₁ × (u₂/u₁)²

= F × [(3 m/s) / (1 m/s)]²

= F × 9

= 9F

Answer 2

$\large\blue{heya mate!!}$

Stopping distance is given as

x = u²/(2a)

Acceleration (a) from Newton's second law is given as

a = F/m

So,

x = u²/(2F/m)

F = u²m/(2x)

From above relation, for a body of mass "m" with constant stopping distance "x",

F ∝ u²

F₂/F₁ = (u₂/u₁)²

F₂ = F₁ × (u₂/u₁)²

= F × [(3 m/s) / (1 m/s)]²

= F × 9

= 9F