Question

plz zzz help me...... ​

Answer 1

Given:-

Mass of the car = 1000kg

Initial velocity (u) = 72km/h

Distance covered (s) = 40m

To Find:-

The average acceleration.

The average breaking force.

Solution:-

Converting 72km/h to m/s

= $\rm 72 \times \dfrac{5}{18}$

= 20m/s

Initial velocity (u) = 20m/s

Final velocity (v) = 0m/s (The car comes to rest)

According to the 2nd equation of motion:-

$\rm \dashrightarrow {v}^{2} = {u}^{2} + 2as$

$\rm \dashrightarrow {0}^{2} = {(20)}^{2} + 2a(40)$

$\rm \dashrightarrow {0} = 400 + 80a$

$\rm \dashrightarrow 80a = - 400$

$\rm \dashrightarrow a= \dfrac{ - 400}{80}$

$\rm \dashrightarrow a= - 5$

$\underline{\boxed{\pink{\rm \therefore Average \: acceleration = -5m/s^{2}}}}$

Now, Average breaking force:-

Breaking force = Mass × Acceleration

= 1000 × -5

= -5000N

$\underline{\boxed{\purple{\rm \therefore Average\: breaking\: force = -5000N}}}$

Answer 2

Acceleration is -5m/s2
Force is -5000 N

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