Question

a car initially moving with a velocity of 20m/ s travels 6 m distance in 4th second then acceleration of car is​

Answer 1

Answer:

a = -4 m/s²

Explanation:

Given :

A car initially moving with a velocity of 20 m/s travels 6 m distance in 4th second.

To find :

the acceleration of car

Solution :

initial velocity, u = 20 m/s

distance travelled in 4th second, S₄ = 6 m

The distance travelled in nth second is given by,

  $\boxed{\tt S_n=u+a\bigg(n-\dfrac{1}{2} \bigg)}$

where

u denotes initial velocity

a denotes acceleration

Substitute the values,

  $\sf 6=20+a \bigg(4-\dfrac{1}{2} \bigg) \\\\ \sf 6-20=a \bigg(\dfrac{8-1}{2} \bigg) \\\\ \sf -14=a \times \dfrac{7}{2} \\\\ \sf a=-14 \times \dfrac{2}{7} \\\\ \sf a=-2 \times 2 \\\\ \sf a=-4 \ m/s^2$

The negative value of acceleration shows that the velocity of a car is decreasing.