MCQ
Rocket engines lift a rocket from the earth surface because hot gas with high velocity
  • A
    Push against the earth
  • B
    Push against the air
  • React against the rocket and push it up
  • D
    Heat up the air which lifts the rocket

Answer

Correct option: C.
React against the rocket and push it up
c
(c)It works on the principle of conservation of momentum.

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

A particle is in linear simple harmonic motion between two points A and B, 10cm apart Take the direction from A to B as the + ve direction and choose the correct statements:

  1. The sign of velocity, acceleration and force on the particle when it is 3cm away from A going towards B are positive.
  2. The sign of velocity of the particle at C going towards O is negative.
  3. The sign of velocity, acceleration and force on the particle when it is 4cm away from B going towards A are negative.
  4. The sign of acceleration and force on the particle when it is at point B is negative.
A man raises a box of mass 50kg to a height of 2m in 2minthes, while another man raises the same box to the same height in 5minthes. What is the ratio of work done by them?
A horizontal force of $5 \,N$ is required to maintain a velocity of $2 \,m/s$ for a block of $10 \,kg$ mass sliding over a rough surface. The work done by this force in one minute is....$J$
Two masses of $5\, kg$ and $3\, kg$ are suspended with the help of massless inextensible strings as shown in figure. The whole system is going upwards with an acceleration of $2\, ms^{-2}$. The tensions $T_1$ and $T_2$ are respectively (Take $g = 10\, ms^{-2}$)
A simple pendulum having length $\ell $ is having speed  $\sqrt {2g\ell }$ at bottom most point of its trajectory. Its motion will be
A swimmer wants to cross a river from point $A$ to point $B$. Line $A B$ makes an angle of $30^{\circ}$ with the flow of river. Magnitude of velocity of the swimmer is same as that of the river. The angle $\theta$ with the line ${AB}$ should be $^{\circ}$, so that the swimmer reaches point ${B}$.
If the maximum velocity and maximum acceleration of a particle executing $SHM$ are equal in magnitude, the time period will be .... $\sec$
Figure shows two capacitors connected in series and joined to a battery. The graph shows the variation in potential as one moves from left to right on the branch containing the capacitors:


  1. C1 > C2
  2. C1 = C2
  3. C1 < C2
  4. The information is not sufficient to decide the relation between C1 and C2.
The temperature of a liquid drops from $365K$ to $361 K$ in $2$ minutes. Find the time during which temperature of the liquid drops from $344\;K$ to $342K$. Temperature of room is $293\;K$  ....... $\sec$
If a particle of mass $m$ is moving in a horizontal circle of radius $r$ with a centripetal force $( - k/{r^2})$, the total energy is