MCQ
Three forces are acting simultaneously at one point. Two forces $\overrightarrow{ P }, \overrightarrow{ Q }$ are $(2 \hat{i}-3 \hat{j})$ and $(\hat{i}-\hat{j})$ respectively. If the object is in equilibrium then which will be the third:
  • A
    $i-2 j$
  • $-3 i+4 j$
  • C
    $2 \hat{i}-2 \hat{j}$
  • D
    $3 \hat{i}+4 \hat{j}$

Answer

Correct option: B.
$-3 i+4 j$
(B)Forequilibrium
$
\begin{aligned}
\overrightarrow{P}+\overrightarrow{Q}+\overrightarrow{R} & =0 \\
\overrightarrow{R} & =-(\overrightarrow{P}+\overrightarrow{Q}) \\
& =-(2 \hat{i}-3 \hat{j}+\hat{i}-\hat{j}) \\
& =-(3 \hat{i}-4 \hat{j}) \\
& =-3 i+4 j
\end{aligned}
$
Hence, the correct option is (B).

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free

Similar questions

First overtone frequency of a closed organ pipe is equal to the first overtone frequency of an open organ pipe. Further nth harmonic of closed organ pipe is also equal to the mth harmonic of open pipe, where $n$ and $m$ are:
A particle starting from the origin $(0,0)$ moves in a straight line in the $(x, y)$ plane. Its coordinates at a later time are $(\sqrt 3,3)$ . The path of the particle makes with the $x -$ axis an angle of  ....... $^o$
$ABC$ is an equilateral triangle. Length of each side is $a$ and centroid is point $O$. Find If $|\overrightarrow{A B}+\overrightarrow{B C}+\overrightarrow{A C}|=n a$ then $n =$ ?
A uniform disc of mass $M$ and radius $R$ is rotating about a horizontal axis passing through its centre with angular velocity $\omega $. A piece of mass $m$ breaks from the disc and flies off vertically upwards. The angular speed of the disc will be
When two capillary tubes of different diameters are dipped vertically, the rise of the liquid is
Moment of inertia of a square plate of side $l$ about the axis passing through one of the corner and perpendicular to the plane of square plate is given by
The least count of a stop watch is $0.2\, second$. The time of $20\, oscillations$ of a pendulum is measured to be $25\, second$. The percentage error in the measurement of time will be  ........ $\%$
The temperature drop through each layer of a two layer furnace wall is shown in figure. Assume that the external temperature $T_1$ and $T_3$ are maintained constant and $T_1 > T_3$. If the thickness of the layers $x_1$ and $x_2$ are the same, which of the following statements are correct.
One mole of an ideal gas in initial state $\mathrm{A}$ undergoes a cyclic process $A B C A$, as shown in the figure. Its pressure at $A$ is $\mathrm{P}_0$. Choose the correct option$(s)$ from the following

$(A)$ Internal energies at $\mathrm{A}$ and $\mathrm{B}$ are the same

$(B)$ Work done by the gas in process $\mathrm{AB}$ is $\mathrm{P}_0 \mathrm{~V}_0 \ln 4$

$(C)$ Pressure at $C$ is $\frac{P_0}{4}$

$(D)$ Temperature at $\mathrm{C}$ is $\frac{\mathrm{T}_0}{4}$

The ratio of the magnitude of potential energy and kinetic energy of a satellite is: