Question

man on his motorbike having a combined mass of 250 kg, moves along a straight road with a uniform speed of
54 km/hr. After sometime, he takes a U turn and continues to move at same speed. The time taken by him in
aking U turn is 12 seconds. The magnitude of average impulse, during U turn is :

Answer 1

Answer:

250(54-(-54))/(60x60) = 7500 N-S,

= 7.5 KN-S.

Answer 2

Given:

Man on his motorbike having a combined mass of 250 kg, moves along a straight road with a uniform speed of 54 km/hr. After sometime, he takes a U turn and continues to move at same speed. The time taken by him in taking U turn is 12 seconds.

To find:

Average impulse while taking U turn ?

Calculation:

First of all, we will convert unit of velocity from km/hr to m/s:

54 km/hr = 54 × (5/18) = 15 m/s.

Now, change in Momentum of man:

$\therefore \: \Delta P = m(v - u)$

$\implies \: \Delta P = 250( - 15 - 15)$

$\implies \: \Delta P = 250( - 30)$

$\implies \: \Delta P = - 7500 \: kgm {s}^{ - 1}$

Now, average impulse will be :

$\therefore \: I = \dfrac{\Delta P}{t} \times t$

$\implies \: I = \Delta P$

$\implies \: I = - 7500 \:N \:s$

$\implies \: I = - 7.5 \:kN \:s$

So, magnitude of average impulse experienced by the man is 7.5 kN s.