Download App

2. motion in straight line — Physics STD 11 Science — Question

Gujarat BoardEnglish MediumSTD 11 SciencePhysics2. motion in straight line1 Mark
MCQ
A man throws balls with the same speed vertically upwards one after the other at an interval of $2\, seconds$. What should be the speed of the throw so that more than two balls are in the sky at any time (Given $g = 9.8\,m/{s^2}$)
  • A
    At least $0.8 \,m/s$
  • B
    Any speed less than $19.6 \,m/s$
  • C
    Only with speed $19.6\, m/s$
  • ✓
    More than $19.6 \,m/s$
✓

Answer

Correct option: D.
More than $19.6 \,m/s$
d
(d) Interval of ball throw $= 2 \,sec$.

If we want that minimum three (more than two) ball remain in air then time of flight of first ball must be greater than $4\, sec$.

$T > 4\,sec$

$\frac{{2u}}{g} > 4\;sec \Rightarrow u > 19.6\;m/s$

for $u =19.6$. First ball will just strike the ground(in sky)

Second ball will be at highest point (in sky)

Third ball will be at point of projection or at ground (not in sky)

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

Explore more

More "M.C.Q (1 Marks)" from 2. motion in straight line→2. motion in straight line — all question types→Physics STD 11 Science question papers→Gujarat Board STD 11 Science question papers→Gujarat Board question paper generator→

Similar questions

If a gas is taken from $A$ to $C$ through $B$ then heat absorbed by the gas is $8 \,J$. Heat absorbed by the gas in taking it from $A$ to $C$ directly is ............. $J$
→
A very long (length $L$ ) cylindrical galaxy is made of uniformly distributed mass and has radius $R(R < < L).$ A star outside the galaxy is orbiting the galaxy in a plane perpendicular to the galaxy and passing through its centre. If the time period of star is $T$ and its distance from the galaxy's axis is $r,$ then
→
Mark the correct statements:
→
The equation of a sound wave is $y = 0.0015\sin (62.4x + 316\,t)$ The wavelength of this wave is ..... $unit$
→
A tuning fork with frequency $800 \;\mathrm{Hz}$ produces resonance in a resonance column tube with upper end open and lower end closed by water surface. Surface. Successive resonance are observed at length $9.75 \;\mathrm{cm}, 31.25\; \mathrm{cm}$ and $52.75\; \mathrm{cm} .$ The speed of sound in air is ......$m/s$
→
One nanometer is equal to:
→
In case of earth:
→
A hollow sphere of mass $1 \,kg$ and radius $10 \,cm$ is free to rotate about its diameter. If a force of $30 \,N$ is applied tangentially to it, its angular acceleration is (in $rad / s ^2$ )
→
A vessel contains $14\,g$ of nitrogen gas at a temperature of $27^{\circ}\,C$. The amount of heat to be transferred to the gap to double the r.m.s. speed of its molecules will be $......J$ $\left(\right.$ Take $R =8.32\,J\,mol ^{-1} k ^{-1}$ )
→
If temperature of a black body increases from ${7^o}C$ to ${287^o}C$, then the rate of energy radiation increases by
→