Question

Distance travelled by a car moving with velocity 20 m s' in time 4 s when it decelerates at
the rate of 3 m s-2 is equal to:
A 30 m
B) 26 m
C)80
D)56​

Answer 1

Given:-

• Initial velocity ,u = 20m/s

• declaration ,a = 3m/s²

• Time taken ,t = 4s

To Find:-

• Distance travelled , s

Solution:-

By using 2nd equation of motion

• s = ut +1/2at²

Substitute the value we get

→ s = 20×4 + 1/2× (-3)× 4²

→ s = 80 + 1/2×(-3)×16

→ s = 80 + (-3)×8

→ s = 80 - 24

→ s = 56 m

∴ The distance travelled by the car is 56 m

Hence, Option (D) is the correct answer.

Answer 2

Answer:

A car is moving with a Initial Velocity (u) = 20 m/s in Time (t) = 4 seconds with decelration (a) = 3 m/s².

We are supposed to calculate distance travelled (s) by the car.

We have three equations of motion :

• v = u + at
• s = ut + ½ at²
• v² = u² + 2as

Now choose the suitable equation of motion on based on our given data.

Using second equation of motion :

• s = ut + ½ at²

$=> \sf s = 20 \times 4 + \dfrac{1}{2} \times - 3 \times (4)^{2}$

$=>\sf s = 80 + \dfrac{1}{2} \times - 3 \times 16$

$=> \sf s =80 + ( - 3)\times 8$

$=> \sf s =80 - 24$

$=> \sf s = 56 \: meter$

⛬ Distance travelled (s) by the car with Initial Velocity (u) = 20 m/s, Time (t) = 4 seconds, and decelration (a) = 3 m/s² is 56 meters.