CBSE Questions for Class 11 Engineering Physics Motion In A Straight Line Quiz 4 - MCQExams.com

A stone is allowed to fall from the top of a tower and covers half the height of the tower in the last second of its journey. The time taken by the stone to reach the foot of the tower is
  • $$\left( 2-\sqrt { 2 } \right) s$$
  • $$4s$$
  • $$\left( 2+\sqrt { 2 } \right) s$$
  • $$\left( 2\pm \sqrt { 2 } \right) s$$
A particle is thrown vertically upwards from ground. It takes time $${ t }_{ 1 }$$ to reach a height $$h$$. It continues to move and takes time $${ t }_{ 2 }$$ to reach the ground. Its maximum height is

134240.jpg
  • $$\cfrac { g }{ 2 } \cfrac { { t }_{ 1 }+{ t }_{ 2 } }{ 2 } $$
  • $$\cfrac { g }{ 2 } \sqrt { { { t }_{ 1 } }^{ 2 }+{ { t }_{ 2 } }^{ 2 } } $$
  • $$\cfrac { g }{ 8 } { \left( { t }_{ 1 }+{ t }_{ 2 } \right) }^{ 2 }$$
  • $$g({ { t }_{ 1 } }^{ 2 }+{ { t }_{ 2 } }^{ 2 })$$
An aeroplane drops a parachutist. After covering a distance of $$40\ m$$, he opens the parachute and retards at $$2\ m{ s }^{ -2}$$. If he reaches the ground with a speed of $$2\ m{ s }^{ -1 }$$, he remains in the air for about
  • $$16\ s$$
  • $$3\ s$$
  • $$13\ s$$
  • $$10\ s$$
A driver driving a truck at a constant speed of $$20\ m{ s }^{ -1 }$$ suddenly saw a parked car ahead of him by $$95\ m$$. He could apply the brake after some time to produce retardation of $$2.5\ m{ s }^{ -1 }$$.An accident was just avoided, his reaction time is

134243_af7cdb59e00a4bbb9e48f0ebfca268bf.png
  • $$0.5 \ s$$
  • $$0.75\ s$$
  • $$0.8\ s$$
  • $$1\ s$$
After what time will he be able to overtake the bus?
  • $$4 sec$$
  • $$8 sec$$
  • $$12 sec$$
  • $$16 sec$$
A particle accelerates from rest at a constant rate for some time and attains a velocity of $$8  { m }/{ sec }$$. Afterwards it decelerates with the constant rate and comes to rest. If the total time taken is $$4  sec$$, the distance travelled is
  • $$32 m$$
  • $$16 m$$
  • $$4 m$$
  • None of the above
Which one of the following represents the displacement time graph of two objects $$A$$ and $$B$$ moving with zero relative speed?
A particle experiences constant acceleration for $$20$$ seconds after starting from rest. If it travels a distance $${ s }_{ 1 }$$ in the first $$10$$ seconds and distance $${ s }_{ 2 }$$ in the next 10 seconds, then
  • $${ s }_{ 2 }={ s }_{ 1 }$$
  • $${ s }_{ 2 }=2{ s }_{ 1 }$$
  • $${ s }_{ 2 }=3{ s }_{ 1 }$$
  • $${ s }_{ 2 }=4{ s }_{ 1 }$$
Free $$^{238}{U}$$ nuclei kept in a train emit alpha particles. When the train is stationary and a uranium nucleus decays, a passenger measures that the separation between the alpha particles and the recoiling nucleus becomes $$x$$, in $$t$$ time after the decay. If a decay takes places, when the train is moving at a uniform speed $$v$$, the distance between the alpha particle and the recoiling nucleus at a time $$t$$ after the decay, as measured by the passenger will be  
  • $$x+vt$$
  • $$x-vt$$
  • $$x$$
  • depends on the directions of the train
A soldier jumps out from an aeroplane with a parachute. After dropping through a distance of $$19.6\ m$$, he opens the parachute and decelerates at the rate of $$1\ m{ s }^{ -2 }$$. If he reaches the ground with a speed of $$4.6\ m{ s }^{ -1 }$$, how long was he in air?
  • $$10\ s$$
  • $$12\ s$$
  • $$15\ s$$
  • $$17\ s$$
A body of mass $$3kg$$ falls from the multi-storeyed building $$100m$$ high and buries itself $$2m$$ deep in the sand. The time of penetration is
  • $$9sec$$
  • $$0.9sec$$
  • $$0.09sec$$
  • $$10sec$$
Which of the following statements are true for a moving body?
  • If its speed changes, its velocity must change and it must have some acceleration.
  • If its velocity changes, its speed must change and it must have some directions.
  • If its velocity changes, its speed may or may not change, and it must have some acceleration.
  • If its speed changes but direction of motion does not change, its velocity may remain constant.
At $$t=0$$, an arrow is fired vertically upwards with a speed of $$98m{ s }^{ -1 }$$. A second arrow is fired vertically upwards with the same speed at $$t=5s$$. Then, (Take $$g=9.8ms^{-2}$$)
  • the arrows will be at the same height above the ground at $$t=12.5s$$.
  • the two arrows will reach back at their starting points at $$t=20s$$ and $$t=25s$$.
  • the ratio of the speeds of the first and the second arrows at $$t=20s$$ will be $$2:1$$.
  • all are correct.
A stone is dropped into a well in which the level of water is $$h$$ below the top of the well. If $$v$$ is velocity of sound, the time $$T$$ after which the splash is heard is given by
  • $$T=\displaystyle\frac { 2h }{ v }$$
  • $$T=\sqrt { \left( \displaystyle\frac { 2h }{ g } \right) } +\displaystyle\frac { h }{ v }$$
  • $$T=\sqrt { \left( \displaystyle\frac { 2h }{ v } \right) } +\displaystyle\frac { h }{ g }$$
  • $$T=\sqrt { \left( \displaystyle\frac { h }{ 2g } \right) } +\displaystyle\frac { 2h }{ v }$$
Figure shows the $$V-T$$ graph for two particles $$P$$ and $$Q$$. The relative velocity of $$P$$ w.r.t. $$Q$$ is:
181028.png
  • is zero. 
  • is non-zero but constant
  • continuously decreases
  • continuously increases
A balloon starts rising from the ground with an acceleration of $$1.25  { m }/{ { s }^{ 2 } }$$. After $$8 \; s$$, a stone is released from the balloon. The stone will (Taking $$g=10{ m }/{ { s }^{ 2 } }$$)
  • begin to move down after being released
  • reach the ground in $$4$$ $$s$$
  • cover a distance of $$40$$ $$m$$ in reaching the ground
  • will have a displacement of $$50$$ $$m$$
A body travels $$2\  m$$ in the first two second and $$2.20\  m$$ in the next $$4$$ second with uniform deceleration. The velocity of the body at the end of $$9$$ second is
  • $$-10\ { m }/{ s }$$
  • $$-0.20\ { m }/{ s }$$
  • $$-0.40\ { m }/{ s }$$
  • $$-0.80\ { m }/{ s }$$
A stone is just released from the window of a moving train moving along a horizontal straight track .When observed by a person on the ground,the stone will hit the ground following a
  • straight line path
  • circular path
  • parabolic path
  • hyperbolic path
A bomb is released from a horizontal flying aeroplane .The trajectory of bomb as observed from ground is
  • a parabola
  • a straight line
  • a circle
  • a hyperbola
A ball is thrown vertically upwards. It returns $$6  s$$ later. Calculate:$$(i)$$ the greatest height reached by the ball, and $$(ii)$$ the initial velocity of the ball. (Take $$g=10  m  {s}^{-2}$$)
  • (i) $$40$$ $$m$$, (ii) $$30$$ $$m$$ $${s}^{-1}$$
  • (i) $$45$$ $$m$$, (ii) $$30$$ $$m$$ $${s}^{-1}$$
  • (i) $$45$$ $$m$$, (ii) $$60$$ $$m$$ $${s}^{-1}$$
  • (i) $$45$$ $$m$$, (ii) $$20$$ $$m$$ $${s}^{-1}$$
A ball is thrown from rear end of the compartment of train to the front end which is moving at a constant horizontal velocity. An observer $$A$$ sitting in compartment and another observer $$B$$ standing on the ground draw the trajectory. They will have
  • equal horizontal and equal vertical ranges.
  • equal vertical ranges but different horizontal ranges.
  • different vertical ranges but equal horizontal ranges.
  • different vertical ranges and different horizontal ranges.
A rocket is fired upward from the earth's surface such that it creates an acceleration of $$19.6  { m }{ { s }^{- 2 } }$$. If after $$5  s$$, its engine is switched off, the maximum height of the rocket from earth's surface would be
  • $$980\ m$$
  • $$735\ m$$
  • $$490\ m$$
  • $$245\ m$$
From a $$200  m$$ high tower, one ball is thrown upwards with speed of $$10  { m }/{ s }$$ and another is thrown vertically downwards at the same speed simultaneously. The time difference of their reaching the ground will be nearest to
  • $$12 s$$
  • $$6 s$$
  • $$2 s$$
  • $$1 s$$
A car starting from rest accelerates uniformly to acquire a speed $$20\ kmh^{-1}$$ in 30 min. The distance travelled by car in this time interval will be
  • 600 km
  • 5 km
  • 6 km
  • 10 km
  • Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
  • Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
  • Assertion is correct but Reason is incorrect
  • Both Assertion and Reason are incorrect
A particle starts to move in a straight line from a point with velocity $$10 m s^{-1}$$ and acceleration $$-2.0 m s^{-2}$$. Find position(S) and velocity(v) of the particle at $$t = 5$$ s
  • $$S = 25 m, v = 0 m/s$$
  • $$S = -25 m, v = 0 m/s$$
  • $$S = 5 m, v = 10 m/s$$
  • $$S = 0 m, v = 0 m/s$$
A body moves from rest with uniform acceleration and travels 270 m in 3 s. Find the velocity of the body at 10 s after the start.
  • $$600\, m\, s^{-1}$$
  • $$6\, m\, s^{-1}$$
  • $$60\, m\, s^{-1}$$
  • $$100\, m\, s^{-1}$$
A car travels a distance $$100 m$$ with a constant acceleration and average velocity of $$20\ ms^{-1}$$. The final velocity acquired by the car is $$25\ ms^{-1}$$. Find the initial velocity.
  • $$15 \,m \,s^{-1}$$
  • $$10 \,m \,s^{-1}$$
  • $$30 \,m \,s^{-1}$$
  • $$0 \,m \,s^{-1}$$
(a) How long will a stone take to fall to the ground from the top of a building $$80  m$$ high and (b) what will be the velocity of the stone on reaching the ground? (Take $$g=10  m  {s}^{-2}$$)
  • (a) $$14$$ $$s$$, (b) $$30$$ $$m$$ $${s}^{-1}$$
  • (a) $$4$$ $$s$$, (b) $$30$$ $$m$$ $${s}^{-1}$$
  • (a) $$10$$ $$s$$, (b) $$40$$ $$m$$ $${s}^{-1}$$
  • (a) $$4$$ $$s$$, (b) $$40$$ $$m$$ $${s}^{-1}$$
A ball is thrown vertically upwards from the top of a tower with an initial velocity of $$19.6  m  {s}^{-1}$$. The ball reaches the ground after $$5  s$$. Calculate :$$(i)$$ the height of the tower, $$(ii)$$ the velocity of ball on reaching the ground. Take $$g=9.8  m  {s}^{-2}$$.
  • $$(i) 24.5 m$$, $$(ii) 29.4$$  $$m$$ $${s}^{-1}$$
  • $$(i) 24.5 m$$, $$(ii) 19.4$$  $$m$$ $${s}^{-1}$$
  • $$(i) 24.5 m$$, $$(ii) 28$$ $$m$$ $${s}^{-1}$$
  • $$(i) 25 m$$, $$(ii) 29.4$$  $$m$$ $${s}^{-1}$$
The velocity of an object increases at a constant rate from $$20 m s^{-1}$$ to $$50 m s^{-1}$$in 10 s. Find the acceleration.
  • $$-3 \,m \,s^{-2}$$
  • $$-30 \,m \,s^{-2}$$
  • $$30 \,m \,s^{-2}$$
  • $$3 \,m \,s^{-2}$$
A ball is thrown vertically upwards with an initial velocity of $$49  m  {s}^{-1}$$. Calculate: (i) the maximum height attained, (ii) the time taken by it before it reaches the ground again. (Take $$g=9.8  m  {s}^{-2}$$)
  • (i) 122.5 m, (ii) 10 s
  • (i) 120.5 m, (ii) 10 s
  • (i) 122.5 m, (ii) 20 s
  • (i) 120 m, (ii) 10 s
A boy on a cliff  $$49 m$$ high drops a stone.One second later,he throws a second after the first .They both hit the ground at the same time.With what speed did he throw the second stone?
  • $$12.1 m/s$$
  • $$10 m/s$$
  • $$21.1 m/s$$
  • $$15.1 m/s$$
A stone is thrown vertically upward with an initial velocity of $${40 ms^{-1}}$$,Taking g=$${10 ms^{-2}}$$, find the maximum height reached by the stone.
  • $$100 m$$
  • $$60 m$$
  • $$80 m$$
  • $$120 m$$
The table below shows the speed of a moving vehicle with respect to time.
Speed (m/s)
2
4
6
8
10
Time (s)
1
2
3
4
5
Find the acceleration of the vehicle.
  • $$2 m/s^2$$
  • $$4 m/s^2$$
  • $$6 m/s^2$$
  • $$8 m/s^2$$
A ball is thrown vertically upwards with a velocity of $${20 ms^{-1}}$$ from the top of a multi storey building.The height of the point where the ball is thrown 25 m from the ground.How long will it be before the ball hits the ground ? Take $${g= 10 ms^{-2}}$$. 
  • t=5s
  • t=10s
  • t=15s
  • t=20s
A stone is thrown vertically upwards. When stone is at a height half of its maximum height, its speed is $$\displaystyle 10 \ m/s;$$ then the maximum height attained by the stone is (g= $$\displaystyle 10 \ m/s^{2}$$)
  • $$25\ m$$
  • $$10\ m$$
  • $$15\ m$$
  • $$20\ m$$
A car starts from rest and uniformly accelerates in a straight line. In the first second the car covers a distance of $$2$$ m. The velocity of the car at the end of $$2^{nd}$$ $$second$$ will be
  • $$\displaystyle 4.0\ ms^{-1}$$
  • $$\displaystyle 8.0\ ms^{-1}$$
  • $$\displaystyle 6\ ms^{-1}$$
  • None of these
A stone is allowed to fall from the top of a tower $$100 m$$ high and at the same time another stone is projected vertically upwards from the ground with a velocity of $${25 ms ^{-1}}$$.Calculate where the two stones will meet.(Take $${g=10 m/s^2}$$). 
  • 10 m
  • 40 m
  • 20 m
  • 50 m
An object is sliding down on an inclined plane. The velocity changes at a constant rate from 10 cm/s to 15 cm/s in 2 seconds. What is its acceleration?
  • $$5 cm/s^2$$
  • $$7.5 cm/s^2$$
  • $$2.5 cm/s^2$$
  • $$12.5 cm/s^2$$
If a car at rest accelerates uniformly to a speed of $$144\ km/h$$ in $$20$$ second, it covres a distance of :-
  • $$20\ m$$
  • $$400\ m$$
  • $$1440\ m$$
  • $$2980\ m$$
A ball thrown up vertically returns to the thrower after 6 s Find it's initial velocity.
  • 20 m/s
  • 40 m/s
  • 35 m/s
  • 30 m/s
The unit for the rate of change of velocity is 
  • $$m s^{-2}$$
  • $$m s^{-3}$$
  • $$m s^{-1}$$
  • $$m^{3} s^{-2}$$
According to the following graph, what happens to the distance covered by the body from 0 -10 minutes?

266782.jpg
  • It goes on increasing
  • It goes on decreasing
  • It first increases and then decreases
  • It first decreases and then increases
A body starts from rest is moving under a constant acceleration up to 20 s . If it moves $$S_{1}$$ Distance in first 10 s, and $$S_{2}$$ distance in next 10 s then $$S_{2}$$ will be equal to:
  • $$S_{1}$$
  • $$2S_{1}$$
  • $$3S_{1}$$
  • $$4S_{1}$$
An aeroplane is flying in a horizontal direction at $$600 km/hr$$ at a height of $$6 kms$$ and is advancing towards a point which is exactly over a target on earth. At that instant the pilot releases a ball which on descending the earth strike the target. The falling ball appears-
  • To the pilot in the aeroplane, as falling along a parabolic path
  • To a person standing near the target, as falling exactly vertical
  • To a person standing near the target, as describing a parabolic path
  • To the pilot sitting in the aeroplane, as falling in a zigzag path
A particle travels $$10\ m$$ in first $$5\ s$$, $$10\ m$$ in next $$3\ s$$. Assuming constant acceleration, what is the distance traveled in the next two seconds.
  • $$\displaystyle \frac{20}{3}\ m$$
  • $$20\ m$$
  • $$60\ m$$
  • $$180\ m$$
A body travels $$200\ cm$$ in the first two seconds and $$220\ cm$$ in the next $$4\ s$$ with same acceleration.The velocity of the body at the end of the $$7^{th}$$ second is 
  • $$5\ cm/s$$
  • $$10\ cm/s$$
  • $$15\ cm/s$$
  • $$20\ cm/s$$
The distance between them at time $$t$$ is:-
  • $$\;\sqrt{(200)^2+(100)^2}\:m$$
  • $$\;\sqrt{(200-4t)^2+(100-2t)^2}\:m$$
  • $$\;[(200-4\,t)+(100-2\,t)]\:m$$
  • $$\;\sqrt{(200-2\,t)^2+(100-4\,t)^2}\:m$$
The rate of change of velocity of an object with respect to time is called ..........
  • Momentum
  • Displacement
  • Acceleration
  • Impulse
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