Question

A car of mass 1000kg and a bus of
mass 8000kg are moving with the
same velocity of 36km/h. find the forces to stop both the car
and the bus in 5s.​

Answer 1

Question:-

A car of mass 1000kg and a bus of mass 8000kg are moving with the same velocity of 36km/hr. find the forces to stop both the car and the bus in 5s.

Given data:-

[ m = mass; u = initial velocity; v = final velocity; a = acceleration; t = time; F = force ]

Here, { According to question }

• 'm' of car = 1000 kg
• 'm' of bus = 8000 kg
• 'v' = 0 km/hr
• 'u' = 36 km/hr
• ' t ' = 5 sec

Solution:-

• 'u' = 36 km/hr [convert in 'm/s']
• 'u' = [ {36×1000}/{60×60} ] m/s
• 'u' = [ 36000/3600 ] m/s
• 'u' = 10 m/s

Now we use, scalar form for motion in one dimrnsion (linear motion)

• v = u + at

{According to given data}

• 0 = 10 + a × 5
• - 10 = 5a i.e.
• 'a' = - 10/5
• 'a' = - 2 sec

Now, to find force acting on car to stop it in 5 sec

{ We know F = m × a }

Now,

• F = m × a
• F = 1000 × ( - 2 )
• F = - 2000 N

To find force acting on bus to stop it in 5 sec

• F = m × a
• F = 8000 × ( - 2 )
• F = - 16000 N

The forces to stop both the car and the bus in 5s, are - 2000 N and

- 16000 N respectively.

{ Note :- Negative sign indicate that, the force act's in opposite direction.}