question_answer 1)
A particle moving in a straight line covers half the distance with speed of 3 m/s. The other half of the distance is covered in two equal time intervals with speed of 4.5 m/s and 7.5 m/s respectively. The average speed of the particle during this motion is [IIT 1992]
A)
4.0 m/s done
clear
B)
5.0 m/s done
clear
C)
5.5 m/s done
clear
D)
4.8 m/s done
clear
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question_answer 2)
The acceleration of a particle is increasing linearly with time \[t\] as \[bt\]. The particle starts from the origin with an initial velocity \[{{v}_{0}}\] The distance travelled by the particle in time \[t\] will be [CBSE PMT 1995]
A)
\[{{v}_{0}}t+\frac{1}{3}b{{t}^{2}}\] done
clear
B)
\[{{v}_{0}}t+\frac{1}{3}b{{t}^{3}}\] done
clear
C)
\[{{v}_{0}}t+\frac{1}{6}b{{t}^{3}}\] done
clear
D)
\[{{v}_{0}}t+\frac{1}{2}b{{t}^{2}}\] done
clear
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question_answer 3)
The motion of a body is given by the equation \[\frac{dv(t)}{dt}=6.0-3v(t)\]. where \[v(t)\] is speed in \[m/s\] and \[t\] in \[\sec \]. If body was at rest at \[t=0\] [IIT-JEE 1995]
A)
The terminal speed is 2.0 \[m/s\] done
clear
B)
The speed varies with the time as \[v(t)=2(1-{{e}^{-3t}})m/s\] done
clear
C)
The speed is \[0.1m/s\] when the acceleration is half the initial value done
clear
D)
The magnitude of the initial acceleration is \[6.0m/{{s}^{2}}\] done
clear
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question_answer 4)
A particle of mass \[m\] moves on the x-axis as follows : it starts from rest at \[t=0\] from the point \[x=0\] and comes to rest at \[=(u+at)t+\frac{1}{2}a{{t}^{2}}\] at the point \[x=1\]. No other information is available about its motion at intermediate time \[(0<t<1)\]. If \[\alpha \] denotes the instantaneous acceleration of the particle, then [IIT-JEE 1993]
A)
\[\alpha \] cannot remain positive for all \[t\] in the interval \[0\le t\le 1\] done
clear
B)
\[|\alpha |\] cannot exceed 2 at any point in its path done
clear
C)
\[|\alpha |\] must be \[\ge 4\] at some point or points in its path done
clear
D)
\[\alpha \] must change sign during the motion but no other assertion can be made with the information given done
clear
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question_answer 5)
A particle starts from rest. Its acceleration versus time (t) is as shown in the figure. The maximum speed of the particle will be
[IIT-JEE (Screening) 2004]
A)
110 m/s done
clear
B)
55 m/s done
clear
C)
550 m/s done
clear
D)
660 m/s done
clear
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question_answer 6)
A car accelerates from rest at a constant rate \[\alpha \]for some time, after which it decelerates at a constant rate \[\beta \]and comes to rest. If the total time elapsed is t, then the maximum velocity acquired by the car is [IIT 1978; CBSE PMT 1994]
A)
\[\left( \frac{{{\alpha }^{2}}+{{\beta }^{2}}}{\alpha \beta } \right)\,t\] done
clear
B)
\[\left( \frac{{{\alpha }^{2}}-{{\beta }^{2}}}{\alpha \beta } \right)\,t\] done
clear
C)
\[\frac{(\alpha +\beta )\,t}{\alpha \beta }\] done
clear
D)
\[\frac{\alpha \beta \,t}{\alpha +\beta }\] done
clear
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question_answer 7)
A stone dropped from a building of height \[h\] and it reaches after \[t\] seconds on earth. From the same building if two stones are thrown (one upwards and other downwards) with the same velocity u and they reach the earth surface after \[{{t}_{1}}\] and \[{{t}_{2}}\] seconds respectively, then [CPMT 1997; UPSEAT 2002; KCET 2002]
A)
\[t={{t}_{1}}-{{t}_{2}}\] done
clear
B)
\[t=\frac{{{t}_{1}}+{{t}_{2}}}{2}\] done
clear
C)
\[t=\sqrt{{{t}_{1}}{{t}_{2}}}\] done
clear
D)
\[t=t_{1}^{2}t_{2}^{2}\] done
clear
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question_answer 8)
A ball is projected upwards from a height \[h\] above the surface of the earth with velocity \[v\]. The time at which the ball strikes the ground is
A)
\[\frac{v}{g}+\frac{2hg}{\sqrt{2}}\] done
clear
B)
\[\frac{v}{g}\left[ 1-\sqrt{1+\frac{2h}{g}} \right]\] done
clear
C)
\[\frac{v}{g}\left[ 1+\sqrt{1+\frac{2gh}{{{v}^{2}}}} \right]\] done
clear
D)
\[\frac{v}{g}\left[ 1+\sqrt{{{v}^{2}}+\frac{2g}{h}} \right]\] done
clear
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question_answer 9)
A particle is dropped vertically from rest from a height. The time taken by it to fall through successive distances of 1 m each will then be [Kurukshetra CEE 1996]
A)
All equal, being equal to \[\sqrt{2/g}\] second done
clear
B)
In the ratio of the square roots of the integers 1, 2, 3..... done
clear
C)
(c) In the ratio of the difference in the square roots of the integers i.e. \[\sqrt{1},\,(\sqrt{2}-\sqrt{1}),\,(\sqrt{3}-\sqrt{2}),\,(\sqrt{4}-\sqrt{3})\]... done
clear
D)
In the ratio of the reciprocal of the square roots of the integers i.e.,. \[\frac{1}{\sqrt{1}},\,\frac{1}{\sqrt{2}},\frac{1}{\sqrt{3}},\,\frac{1}{\sqrt{4}}\] done
clear
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question_answer 10)
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 \[g=9.8m/{{s}^{2}})\] [CBSE PMT 2003]
A)
At least 0.8 m/s done
clear
B)
Any speed less than 19.6 m/s done
clear
C)
Only with speed 19.6 m/s done
clear
D)
More than 19.6 m/s done
clear
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question_answer 11)
If a ball is thrown vertically upwards with speed \[u\], the distance covered during the last \[t\] seconds of its ascent is [CBSE PMT 2003]
A)
\[\frac{1}{2}g{{t}^{2}}\] done
clear
B)
\[ut-\frac{1}{2}g{{t}^{2}}\] done
clear
C)
\[(u-gt)t\] done
clear
D)
\[ut\] done
clear
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question_answer 12)
A small block slides without friction down an inclined plane starting from rest. Let \[{{S}_{n}}\]be the distance travelled from time \[t=n-1\] to \[t=n.\] Then \[\frac{{{S}_{n}}}{{{S}_{n+1}}}\] is [IIT-JEE (Screening) 2004]
A)
\[\frac{2n-1}{2n}\] done
clear
B)
\[\frac{2n+1}{2n-1}\] done
clear
C)
\[\frac{2n-1}{2n+1}\] done
clear
D)
\[\frac{2n}{2n+1}\] done
clear
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