Question

Calculate the force exerted by the brakes on the motorcar which is moving with a velocity of 72 km/h and takes 5s to stop after the application of brakes. Mass of the motorcar along with the passengers is 800 kg. *

Answer 1

Explanation:

u = 72 km/hr = 20 m/s

v = 0 m/s

t = 5 s

$a = \frac{v - u}{t} = \frac{0 - 20}{5} = - 4 \: m {s}^{ - 2}$

Here, the - sign indicates that the body is retarding.

Mass = 800 kg.

$force = mass \times acceleration$

$= 800 \times 4 = 3200 \: n$

Therefore , the force applied by the brakes is 3200 N.

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Answer 2

Answer:

u = 72 km/hr = 20 m/s

v = 0 m/s

t = 5 s

a = \frac{v - u}{t} = \frac{0 - 20}{5} = - 4 \: m {s}^{ - 2}a=

t

v−u

=

5

0−20

=−4ms

−2

Here, the - sign indicates that the body is retarding.

Mass = 800 kg.

force = mass \times accelerationforce=mass×acceleration

= 800 \times 4 = 3200 \: n=800×4=3200n

Therefore , the force applied by the brakes is 3200 N.

Explanation:

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