MCQ
A particle of mass $2\, kg$ is initially at rest. A force acts on it whose magnitude changes with time. The force time graph is shown below. The velocity of the particle after $10\, s$ is ......... $ms^{-1}$
- A$20$
- B$10$
- C$75$
- ✓$50$
✓
Answer
Correct option: D.
$50$
d
Area under the $F-t$ curve $=$ change in momentum
Area under the $F-t$ curve $=$ change in momentum
or $\frac{1}{2} \times 2 \times(10)+2 \times 10+\frac{1}{2}(10+20) \times 2+\frac{1}{2} \times 4 \times 20$
$=\mathrm{m}(\mathrm{v}-\mathrm{u})$
$\begin{array}{ll}{\text { or } 10+20+30+40=} & {2(\mathrm{v}-0)} \\ {\text { or }} & {100=2 \mathrm{v}}\end{array}$
or $\mathrm{v}=50 \mathrm{ms}^{-1}$
Need a full question paper?
Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.
Explore more
Similar questions
A bar magnet when placed at an angle of $30^o$ to the direction of magnetic field induction of $5 \times 10^{-2} \,T$, experiences a moment of couple $25 \times 10^{-6} \,N-m$. If the length of the magnet is $ 5\, cm $ its pole strength is
→Match List I with List $II$
→Choose the correct answer from the options given below:
When a dc voltage of $100 \mathrm{~V}$ is applied to an inductor, a dc current of $5 \mathrm{~A}$ flows through $1$ . When an ac voltage of $200 \mathrm{~V}$ peak value is connected to inductor, its inductive reactance is found to be $20 \sqrt{3} \Omega$. The power dissipated in the circuit is__________.$W$.
→When electric bulbs of same power, but different marked voltage are connected in series across the power line, their brightness will be :
The Rydberg constant $R$ for hydrogen is
→An electron is moving along positive $x$-axis. To get it moving on an anticlockwise circular path in $x-y$ plane, a magnetic filed is applied
→$Assertion :$ For a particle performing $SHM$, its speed decreases as it goes away from the mean position.
$Reason :$ In $SHM$, the acceleration is always opposite to the velocity of the particle.
→$Reason :$ In $SHM$, the acceleration is always opposite to the velocity of the particle.
Assertion $(A):$ Forces acting between proton-protn $\left(f_{p p}\right)$, proton-neutron $\left(f_{p p}\right)$ and neutron-neutron $\left(f_{n n}\right)$ are such that $f_{p p} < f_{p n}=f_{n n}$
→Reason $(R):$ Electrostatic force of repulsion between two protons reduces net nuclear forces between them.
A small mirror of mass $m$ is suspended by a massless thread of length $l$. Then the small angle through which the thread will be deflected when a short pulse of laser of energy $E$ falls normal on the mirror
($\mathrm{c}=$ speed of light in vacuum and $\mathrm{g}=$ acceleration due to gravity)
→($\mathrm{c}=$ speed of light in vacuum and $\mathrm{g}=$ acceleration due to gravity)
Four uniform wires of the same material are stretched by the same force. The dimensions of wire are as given below. The one which has the minimum elongation has