JEE Main Physics - Description of Motion in One Dimension
Exam Duration: 60 Mins Total Questions : 30
A locomotive begins to move with uniform acceleration at the moment when a boy runs past it with uniform velocity 2 \(ms^{-1}\). The velocity of the locomotive when it overtakes the boy is
- (a)
2 \(ms^{-1}\)
- (b)
4 \(ms^{-1}\)
- (c)
6 \(ms^{-1}\)
- (d)
8 \(ms^{-1}\)
A body is falling from rest in a medium is described by \({dv\over dt}=a-bv,\) where a and b are constants. The velocity at any time is
- (a)
\({a\over b}(1-e^{-M})\)
- (b)
\(a(1-b^{24})\)
- (c)
\(abe^{-t}\)
- (d)
\(ab^2(1-t)\)
A freely falling body, falling from a tower of height h covers a distance h/2 in the last second of its motion. So, height of a tower is
- (a)
58 m
- (b)
50 m
- (c)
60 m
- (d)
55 m
The displacement (x) of a particle depends on time t as \(x=\propto t^2-\beta^3.\) Choose the incorrect statement from the following.
- (a)
The particle return to its starting point
- (b)
The particle come to rest after time \(2\alpha\over 3 \beta\)
- (c)
The initial velocity of the particle is zero
- (d)
The initial acceleration of the particle is zero
The displacement of a particle moving in a straight line depends on time \(x=\alpha t^3+\beta t^2+\gamma t+\delta \). The ratio of initial acceleration to its initial velocity depends
- (a)
\(on\ \alpha\ and\ \gamma\)
- (b)
\(on\ \beta\ and\ \gamma\)
- (c)
\(on\ \gamma\ and\ \beta\)
- (d)
\(only\ on\ \alpha\)
The acceleration \(\alpha\) in \(m/s^2\) of a particle is given by \(a=3t^2+2^t+2,\) where t is the time. If the particle starts out with a velocity \(v=2\ m/s\) at \(t=0\), then find the velocity at the end of 2 s.
- (a)
18 m/s
- (b)
30 m/s
- (c)
24 m/s
- (d)
40 m/s
A stone is dropped from the top of a tower of height h. After I second another stone is dropped from the balcony 20 m below the top. Both reach the bottom simultaneously. What is the value of h? (Take g = 10m s-2)
- (a)
3125 m
- (b)
312.5 m
- (c)
31.25 m
- (d)
25.31 m
If two balls of same density but different masses are dropped from a height of 100 m, then :
- (a)
both will come together on the eart
- (b)
both will come late on the earth
- (c)
first will come first and second after that
- (d)
second will come first and first after that
A particle moves along a straight line such that it displacement at any time t is given by:
s = (t3 - 3t2 + 2)m The displacement when the acceleration becomes zero is:
- (a)
0 m
- (b)
2 m
- (c)
3 m
- (d)
-2 m
An object accelerates from rest to a velocity 27.5 m/s in 10 see, then find distance covered by next 10 see:
- (a)
550 m
- (b)
137.5 m
- (c)
412 .5 m
- (d)
275 m
A coin is dropped in a lift. It takes time t1 to reach the floor when lift is stationary. It takes time t2 when lift is moving up with constant acceleration, then:
- (a)
t1=t2
- (b)
t1>t2
- (c)
t2>t1
- (d)
t1>>t2
A driver applies the brakes on seeing traffic signal 400 m ahead. At the time of applying the brakes vehicle was moving with 15 ms-1 and retarding with 0.3 m s-2. The distance of vehicle after 1 minute from the traffic light is:
- (a)
25 m
- (b)
375 m
- (c)
360 m
- (d)
40 m
The displacement of a body along x-axis depends on time as √x=t+1. Then the velocity of body:
- (a)
increases with time
- (b)
decreases with time
- (c)
independent of time
- (d)
none of these
A particle is moving on a straight line path with constant acceleration directed along the direction of instantaneous velocity. Choose the correct statement from the following
- (a)
Particle may reverse the direction of motion
- (b)
Distance covered = magnitude of displacement
- (c)
Average velocity < average speed
- (d)
Average velocity = instantaneous velocity
For motion on a curved path with constant acceleration (magnitude of displacement /distance covered):
- (a)
>1
- (b)
≥1
- (c)
≤1
- (d)
<1
A particle is thrown vertically upward. Find its velocity so that it covers same distance in 5th and 6th seconds.
- (a)
48 m/s
- (b)
14 m/s
- (c)
49 m/s
- (d)
7 m/s
Two trains A and B initially 120 km apart, start moving towards each other on the same track with a velocity of 60 km/h each. At the moment of start A blows a whistle,
which reflects on B and subsequently reflects from A and so on. Take the velocity of sound waves in air as 1200 km/hr. The distance travelled by sound waves before the trains crash will be:
- (a)
2400 km
- (b)
1200 km
- (c)
240 km
- (d)
120 km
A police car is travelling in a straight line with a constant speed v. A truck travelling in the same direction with constant velocity 3v/2 passes the police car at t = 0. The
police car starts accelerating 10 s after passing the truck, at a constant rate of 3 m/s2, while the truck continues to move at constant speed. If the police car takes 10 s further to catch the truck, find the value of v.
- (a)
10 m/s
- (b)
15 m/s
- (c)
20 m/s
- (d)
30 m/s
A man of height h walks in a straight path towards a lamp post of height H with uniform velocity u. Then the velocity of the edge of the shadow on the ground will be:
- (a)
\(\frac{hu}{(H-h)}\)
- (b)
\(\frac{Hu}{(H+h)}\)
- (c)
\(\frac{(H-h)}{hu}\)
- (d)
\(\frac{(H+h)}{hu}\)
A body of mass 4 kg, is accelerated upon by a constant force, travels a distance of 5 m in the first second and a distance of 2 m in the third second. The force acting on the body is:
- (a)
2 N
- (b)
4 N
- (c)
6 N
- (d)
8 N
A stone falls freely from rest from a height h and it travels a distance \(\frac{9h}{25}\) in the last second. The value of h is :
- (a)
145 m
- (b)
100 m
- (c)
122.5 m
- (d)
200 m
Which of the following velocity-time graphs shows a realistic situation for a body in motion?
- (a)
- (b)
- (c)
- (d)