Impulse MCQ Questions & Answers in Basic Physics | Physics
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21.
If $$a$$ cricketer catches a ball of mass $$150\,gm$$ moving with a velocity of $$20\,m/s,$$ then he experiences a force of (Time taken to complete the catch is $$0.1\,\sec.$$ )
A
$$300\,N$$
B
$$30\,N$$
C
$$3\,N$$
D
$$0.3\,N$$
Answer :
$$30\,N$$
Net force experienced $$ = \frac{{{\text{Total Impulse}}}}{{{\text{Time}}\,{\text{taken}}}}$$
$$ = \frac{{m\Delta v}}{t} = 0.15 \times \frac{{20}}{{0.1}} = 30\,N$$
22.
The force required to stop a car of mass $$800\,kg,$$ moving at a speed of $$20\,m{s^{ - 1}}$$ over a distance of $$25\,m$$ in $$2.5\,\sec$$ is
A
$$1200\,N$$
B
$$6400\,N$$
C
$$1600\,N$$
D
$$1800\,N$$
Answer :
$$6400\,N$$
As we know, $$\left| a \right| = \left| {\frac{{{v^2} - {u^2}}}{{2S}}} \right| = \frac{{400}}{{50}} = 8\,m/{s^2}.$$
So force required $$ = F = ma$$
$$ = 800 \times 8 = 6400\,N$$