Question

a motorcycle us moving with a velocity of 90 km/hr and it takes 5 seconds to stop after the brakes applies. calculate the force exerted by the brakes on the motorcycle if it's mass along with the rider is 200kg​

Answer 1

$\boxed{\rm{\orange{Given \longrightarrow }}}$

• Initial velocity , u = 90 km/h.
• Final velocity , v = 0 m/s.
• Time , t = 5 seconds.
• mass of body , m = 200 kg.

$\boxed{\rm{\red{To\:Find\longrightarrow }}}$

• The force exerted by the brakes on motorcycle , F.

$\boxed{\rm{\pink{solution \longrightarrow }}}$

Here, the final velocity (v) of the motorcycle is “ 0 ” . [Because, brakes are applied on the motorcycle .]

initial velocity (u) = 90km/h = 90 × 5/18 = 25m/s

Time (t) = 5s

$\orange\bigstar\:\rm{\gray{\overbrace{\underbrace{\pink{v\:=\:u\:+\:at\:}}}}}$

$\rm{\implies\:0\:=\:25\:+\:a\times{5}\:}$

$\rm{\implies\:a\times{5}\:=\:-25\:}$

$\rm{\implies\:a\:=\:\dfrac{-25}{5}\:}$

$\rm{\green{\implies\:a\:=\:-5\:m/s^2}}$

[Note :- The -ve sign indicates the deacceleration of the motorcycle.]

⭐ According to Newton's 2nd law motion ,

$\red\bigstar\:\rm{\gray{\overbrace{\underbrace{\pink{Force\:=\:mass\times{acceleration}\:}}}}}$

mass = 200kg

$\rm{\implies\:F\:=\:200\times{-5}\:}$

$\rm{\green{\implies\:F\:=\:-1000\:N}}$

$\rm\pink{\therefore}$The force exerted by the brakes is “ 1000N ”

Answer 2

$\huge\mathtt\red{\underline{\underline{Question}}}$

A motorcycle moving with a velocity of 90km/hr and it takes 5 seconds to stop after the brakes applies. Calculate the force exerted by the brakes on the motorcycle if it's mass along the rider is 200kg?

$\huge\mathtt\orange{Given:-}$

Initial velocity=90km/hr.

$90 \times \frac{5}{18}$

$5 \times 5 = 25ms$

mass=200kg

time=5 seconds

final velocity=0m/s

$\huge\mathtt\pink{\underline{\underline{Answer}}}$

According to 1st equation of motion

v=u+at

0=25+a×5

0=25+5a

5a=-25

$a = \frac{ - 25}{5}$

$a = - 5m {s}^{2}$

According to second law of motion

Force=mass×acceleration

Force=200×(-5)

Force=-1000N

A force of -1000N is being exerted.