Question

A car of mass 1000kg stops after 100 m when driver applied the brake providing 3125 N regarding force. Calculate the initial speed of the car when brake was applied.
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Answer 1

Answer:-

Given:

Mass of the car (m) = 1000 kg

Distance travelled (S) = 100 m

Final velocity (v) = 0 m/s (Breaks are applied).

Force (F) = - 3125 N

(Force will be negative of initial Velocity is greater than final velocity of an object)

We know that,

F = ma

(a is acceleration)

Hence,

⟹ - 3125 = (1000) * a

⟹ - 3125/1000 = a

⟹ - 3.125 m/s² = a

Now,

Using third equation of motion,

i.e., v² - u² = 2aS

⟹ (0)² - u² = 2 * ( - 3.125) * 100

⟹ - u² = - 625

⟹ u = √625

⟹ u = 25 m/s

∴ The initial Velocity of the car is 25 m/s.