Question

4. An object is moving with uniform acceleration.
Its velocity after 4 sis 20 ms-1 and after 7 second
is 29 ms-1. Find the distance travelled by the
object in 10th second.​

Answer 1

Explanation:

Velocity after 4 sec = 20m/s

Velocity after 7 sec = 29m/s

According to the 1st equation of motion:-

⇢ v = u + at

After 4 sec:-

⇢ 20 = u + 4a......(i)

After 7 sec:-

⇢ 29 = u + 7a......(ii)

Subtracting equation (i) from (ii)

⇢ u + 7a - (u + 4a) = 29 - 20

⇢ u + 7a - u - 4a = 9

⇢ 3a = 9

⇢ a = 9/3 = 3m/s²

Substitute a = 3 in equation (i)

⇢ u + 4a = 20

⇢ u + 4(3) = 20

⇢ u + 12 = 20

⇢ u = 20 - 12 = 8m/s

Initial velocity (u) = 8m/s

Acceleration (a) = 3m/s²

The distance traveled by the object in 10th second

Here:- n = 10

⇢ S = u + a ( n - ½ )

⇢ S = 8 + 3 (10 - ½)

⇢ S = 8 + 3 (9.5)

⇢ S = 8 + 28.5

⇢ S = 36.5

∴ Distance traveled by the object in 10th second = 36.5m