A particle covers half of its total distance with speed v_{1} and the rest half distance with speed v_{2}. Its average speed during the complete journey is
v_{1}v_{2 }/ v_{1} + v_{2}
2v_{1}v_{2}/v_{1} + v_{2}
2v_{1}^{2}v^{2}_{2} / v_{1}^{2} + v^{2}_{2}
2v_{1}^{2}v^{2}_{2} / v_{1}^{2} + v^{2}_{2}
A conveyor belt is moving at a constant speed of 2 m/s. A box is gently dropped on it. The coefficient of friction between them is μ = 0.5. The distance that the box - will move relative to belt before coming to rest on it taking
g= 10 ms^{-2 is}
1.2 m
0.6 m
zero
zero
A ball is dropped from a high-rise platform at t=0 starting from rest. After 6s another ball is thrown downwards from the same platform with a speed v. The two balls meet at t= 18s. What is the value of v? (take g= 10 ms^{-2})
74 ms^{-2}
55 ms^{-1}
40 ms^{-1}
40 ms^{-1}
A body of mass 3 kg is under a constant force which causes a displacement s in metres in it, given by the relation , where t is in s. Work done by the force in 2 s is:
A particle moves along a straight line OX. At a time t (in seconds) the distance x (in metres) of the particle from O is given by
How long would the particle travel before coming to rest?
24m
40m
56m
56m
The x and y coordinates of the particle at any time are x = 5t – 2t^{2} and y = 10t respectively, where x and y are in meters and t in seconds. The acceleration of the particle at t = 2 s is
0
5 m/s^{2}
-4 m/s^{2}
-4 m/s^{2}
C.
-4 m/s^{2}
x = 5t – 2t^{2} y = 10t
Acceleration of particle at t = 2 s is = –4 m/s^{2}
A toy car with charge q moves on a frictionless horizontal plane surface under the influence of a uniform electric field $\overrightarrow{E}$ . Due to the force q $\overrightarrow{E}$, its velocity increases from 0 to 6 m/s in one-second duration. At that instant, the direction of the field is reversed. The car continues to move for two more seconds under the influence of this field. The average velocity and the average speed of the toy car between 0 to 3 seconds are respectively
2 m/s, 4 m/s
1 m/s, 3 m/s
1.5 m/s, 3 m/s
1 m/s, 3.5 m/s
The radius of earth is 6400 km and g = 10 m/s^{2}. In order that a body of 5 kg weight is zero at the equator, the angular speed is
$\frac{1}{800}\mathrm{rad}/\mathrm{sec}$
$\frac{1}{1600}\mathrm{rad}/\mathrm{sec}$
$\frac{1}{400}\mathrm{rad}/\mathrm{sec}$
$\frac{1}{80}\mathrm{rad}/\mathrm{sec}$
A wheel rotates with constant acceleration of 2.0 radian/sec^{2} .If the wheel starts from rest the number of revolution it makes in the first ten second, will be approximately
32
24
16
8
A stone is thrown with an initial speed of 4.9m/s from a bridge in vertically upward direction.It falls down in water after 2sec. The height of bridge is
24.7m
19.8 m
9.8 m
4.9 m