Question

4. A car is moving with speed of 20 m/s. After applying the brakes, if the maximum
deceleration produced is 10m/s2,then find the distance covered by the car before coming to rest.​

Answer 1

Answer:

• Distance covered by Car = 20 m

Explanation:

Given:

Car is travelling at 20 m/s, so

• The Initial speed of Car, u = 20 m/s

Deceleration produced in the car is 10 m/s², so

• Acceleration of Car, a = -10 m/s²

Since, Brakes are applied for bringing it to rest, so

• The Final velocity of Car, v = 0 m/s

To find:

• Distance covered by the car before coming to rest, s =?

Formula required:

• Third equation of motion

        2 a s = v² - u²

Where,

a = acceleration

s = distance covered

v = final velocity

u = Initial velocity

Calculation:

Using third equation of motion

→ 2 a s = v² - u²

[ putting values ]

→ 2 × (-10) × s = 0² - (20)²

→ -20 s = 0 - 400

→ s = -400 / -20

→ s = 20 metres

Therefore,

• Distance covered by Car before coming to rest will be 20 metres.

Three equations of motion:

• First equation : v = u + a t
• Second equation : s = u t + 1/2 a t²
• Third equation : 2 a s = v² - u²

Where,

v = final velocity

u = initial velocity

a = acceleration

t = time taken

s = distance covered.