Laws of Motion — Question 7

(i) Velocity (v) = $\dfrac{\text {distance (S)}}{\text {time (t)}}$

Given,

s = 100 m in 5 s

Substituting the values in the formula above we get,

$\text v = \dfrac{100}{5} \\[0.5em] \text v = 20\ \text {m s}^{-1}\\[0.5em]$

Hence, velocity acquired by the body = 20 m s^-1

(ii) As we know,

v² - u² = 2as

Given,

s = 100 m

u = 0

v = 20 m s^-1

Substituting the values in the formula above we get,

$20^2 - 0^2 = 2 \times \text a \times 100 \\[0.5em] 400 = 200 \times \text a \\[0.5em] \Rightarrow \text a = 2\ \text {m s}^{-2} \\[0.5em]$

Hence, a = 2 m s^-2

(iii) As we know,

Force (f) = mass (m) x acceleration (a)

Given,

m = 100 kg

a = 2 m s ^-2

Substituting the values in the formula above we get,

$\text F = 100 \times 2 \\[0.5em] \Rightarrow \text F = 200\ \text N \\[0.5em]$

Hence,

Magnitude of force = 200 N