Question

A car of mass 720 kg moving at a speed of 54 km/h is stopped by applying brakes in 10 second. Calculate the force applied by the brakes. ​

Answer 1

Answer:

–1080 N

Explanation:

Given that,

• Mass of the car (m) = 720 kg
• Initial velocity (u) = 54 km/h
• Time taken (t) = 10 seconds
• Final velocity (v) = 0 m/s (Comes to stop)

Have to calculate,

• Force applied (F).

In order to calculate, the force applied, firstly we need to find the acceleration.

• Acceleration is the rate of change in velocity.

★ a = (v – u)/t

• a = ?
• v = 0 m/s
• u = 54 km/h = (54 × 5/18) m/s = 15 m/s
• t = 10 seconds

→ a = (0 – 15)/10 m/s²

→ a = –15/10 m/s²

→ a = – 1.5 m/s² … 1)

Now, as we know that,

• Force is defined as he product of mass and acceleration.

★ F = ma

• F denotes force
• m denotes mass
• a denotes acceleration

→ F = 720 × (-1.5) N

→ F = –1080 N

Therefore, the force applied by the brakes is 1080 N in the opposite direction.

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