Question

A car starts from rest and attains a velocity of 10 metre per second in 40

seconds .the driver applies brakes and slows down the car to 5 metre per

second in 10 seconds. Find the acceleration of the car in both the cases?.​

Answer 1

Answer:

in first case

a= 10/40

a= 0.25

in second one

a= (5-10)/10

a= -5/10

a= -0.5

Answer 2

SOLUTION:

Considering case (I)

Here,

• Initial velocity of Car = 0
• Final velocity of Car = 10 m/s
• Time taken for change in velocity = 40 sec

We need to find

• acceleration, in this case, a₁ =?

Using the first equation of motion

→ v = u + a t

[ where v represent final velocity, u represent initial velocity, a stands for acceleration and t is the time taken ]

→ 10 = 0 + a₁ × 40

→ 10 = 40 a₁

→ a₁ = 0.25  m/s²

Therefore,

• Acceleration of Car, in this case, would be 0.25 m/s².

Considering case (II)

Here,

• Initial velocity will be equal to the final velocity in the first case that is = 10 m/s
• Final velocity in this case = 5 m/s
• Time taken for the change in velocity = 10 s

We need to find,

• Acceleration of Car, in this case, a₂ =?

Again, Using first equation of motion

→ v = u + a t

→ 5 = 10 + a₂ × 10

→ 5 - 10 = 10  a₂

→ a₂ = -0.5  m/s²

Therefore,

• Acceleration of Car, in this case, would be 0.25 m/s².