Below figure shows the position-time graph of a body of mass $0.04\; kg$. Suggest a suitable physical context for this motion. What is the time between two consecutive impulses received by the body ? What is the magnitude of each impulse ?
A ball rebounding between two walls located between at $x=0$ and $x=2 \,cm ;$ after every
$2$ $s$, the ball receives an impulse of magnitude $0.08 \times 10^{-2} \,kg\, m / s$ from the walls
The given graph shows that a body changes its direction of motion after every $2$ $s$. Physically, this situation can be visualized as a ball rebounding to and fro between twe stationary walls situated between positions $x=0$ and $x=2 \,cm .$ since the slope of the $x-$ graph reverses after every $2$ $s$, the ball collides with a wall after every $2$ $s$. Therefore, bal receives an impulse after every $2$ $s$. Mass of the ball, $m=0.04 \,kg$
The slope of the graph gives the velocity of the ball. Using the graph, we can calculate initial velocity $(u)$ as:
$u=\frac{(2-0) \times 10^{-2}}{(2-0)}=10^{-2}\, m / s$
Velocity of the ball before collision, $u=10^{-2} \,m / s$ Velocity of the ball after collision, $v=-10^{-2} \,m / s$
(Here, the negative sign arises as the ball reverses its direction of motion.) Magnitude of impulse $=$ Change in momentum $=|m v-m u|$
$=|0.04(v-u)|$
$=\left|0.04\left(-10^{-2}-10^{-2}\right)\right|$
$=0.08 \times 10^{-2} \,kg\, m / s$
A spherical body of mass $100 \mathrm{~g}$ is dropped from a height of $10 \mathrm{~m}$ from the ground. After hitting the ground, the body rebounds to a height of $5 \mathrm{~m}$. The impulse of force imparted by the ground to the body is given by : (given $\mathrm{g}=9.8 \mathrm{~m} / \mathrm{s}^2$ )
A particle of mass m moving with a velocity $u$ makes an elastic one dimensional collision with a stationary particle of mass $m$ establishing a contact with it for extremely small time $T$. Their force of contact increases from zero to $F_0$ linearly in time $\frac{T}{4}$, remains constant for a further time $\frac{T}{2}$ and decreases linearly from $F_0$ to zero in further time $\frac{T}{4}$ as shown. The magnitude possessed by $F_0$ is
Displacement of a particle of mass $2\, kg$ moving in a straight line varies with time as $s = (2t^3 + 2)\, m$. Impulse of the force acting on the particle over a time interval between $t = 0$ and $t = 1\, s$ is .......... $N-s$
A soldier with a machine gun, falling from an alrplane gets detached from his parachute. He is able to resist the downward acceleration, if he shoots $40$ bullets a second at the speed of $500 \,m / s$. If the weight of a bullet is $49 \,g$, the weight of the man .......... $ \,kg$ with the gun? Ignore resistance due to air and assume the acceleration due to gravity, $g=9.8 \,ms ^{-2}$.
In a tug-of-war contest, two men pull on a horizontal rope from opposite sides. The winner will be the man who