Question

an object starts moving from rest with uniform accelerationand travels 20 m in 2secs what will be its velocity after 10 secs from the start and displacement in the 10th second

Answer 1

Answer:

Velocity after 10 s = 100 $m s^{-1}$

Displacement in the 10th second = 95 m

Explanation:

S = 20 m

t = 2 s

u = 0

v = ?

Using the second kinematic equation, find the acceleration.

S = ut + $\frac{1}{2}$at²

⇒ 20 m = 0×2 + $\frac{1}{2}$a×2²

⇒ 20 m = $\frac{1}{2}$a×4

⇒ a = $\frac{20}{2}$

⇒ a = 10 m/s²

Using the first kinematic equation, find velocity after 10 s.

v = u + at

⇒ v = 0 + 10×10

⇒ v = 100 $m s^{-1}$

∴ Velocity after 10 s = 100 $m s^{-1}$

The formula for displacement in nth second is given by:

Sₙ = u + $\frac{a}{2}$(2n - 1)

where, u = 0

n = 10 s

a = 10 $m s^{-2}$

⇒ Sₙ = $\frac{10}{2}$(2×10 - 1)

⇒ Sₙ = 5 × 19

⇒ Sₙ = 95 m

∴ The displacement in the 10th second is 95 m.

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