A particle has initial velocity 3i^+4j^ and has acceleration 0.4i^+0.3j^. Its speed after 10s is 

(a) 7unit                                                         (b) 72unit

(c) 8.5 unit                                                     (d) 10 unit

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The speed of a projectile at its maximum height is half of its initial speed. The angle of projection is:

  •  60°                                         

  •  15°

  •  30°                                         

  •  45°

A particle moves in the x-y plane according to rule x=asinωt and y=acosωt. The particle follows:

  • an elliptical path.

  • a circular path.

  • a parabolic path.

  • a straight line path inclined equally to the x and y-axis.

The x and y coordinates of the particle at any time are x=5t-2t2 and y = 10 t respectively, where x and y are in meters and t in seconds. The acceleration of the particle at t = 2 s is

  • 0

  • m/s2

  • -4 m/s2

  • -8 m/s2

Drops of water fall from the roof of a building 20 m high at regular intervals

of time. The first drop reaching the ground at the same instant fifth drop

starts its fall. What are the distance  of second and third drops from roof? (g =

10 m/s2)

  • 1. 5.0 m and 1.25 m

  • 5.0 m and 2.25 m

  • 11.25 m and 5.0 m

  • 11.25 and 1.25 m

A particle is dropped vertically from rest from a height. The time taken by it to

fall through successive distances of 1 m will the be

  • All equal, being equal to 2/g second

  • In the ratio of the square roots of integers 1,2,3....

  • In the ratio of the difference in the square roots of the integers i.e. 1, 2-13-24-3

  • In the ratio of the reciprocal of the square roots of the integers, i.e., 11 , 12 ,13 ,  14 

A ball rolls off the top of stairway with a horizontal velocity of magnitude 1.8 m/s. The steps are 0.20 m high and 0.20 m wide. Which step will the ball hit first ?

  • 1. First

  • Second

  • Third

  • Fourth

A car accelerates from rest at a constant rate α for some time after which it decelerates at a constant rate β to come to rest. If the total time elapsed is t, the distance travelled by the car is:

  • 1. 12αβα+βt2

  •  12α+βαβt2

  •  12α2+β2αβt2

  •  12α2-β2αβt2

A train accelerates from rest at a constant rate α for distance x1 and time ti. After that, It retards to rest at a constant rate β for distance x2 and time t2. Then it is found that

  •  x1x2 = αβ = t1t2

  •  x1x2 = βα = t1t2

  •  x1x2 = βα = t2t1

  • x1x2 = αβ = t2t1

A man in a lift ascending with an acceleration throws a ball vertically upwards with a velocity u and catches it after time t1. Afterwards, when the lift is descending with the same acceleration, the man again throws the ball vertically upwards and catches it after time t2. The velocity of the projection of the ball:

1. gt1t2t1-t22. gt1t2t1+t23. gt1t22t1-t24. gt1t22t1+t2

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A vertical circular disc has different grooves along various chords as shown in fig. The particles are released from upper end O. The times taken by the particles to reach the ends of the grooves OA, OB and OC respectively are in the ratio

  • 1. 1:1:1

  • 1:2:3

  • 1: 3:2

  • 1: 3: 2

A ball is dropped vertically from a height above the ground. It hits the ground and bounced up vertically to a height d/2. neglecting subsequent motion and the air resistance, its velocity v with height h above the ground can be represented as 

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In the given figure, a = 15m /s2 represents the total acceleration of a particle moving in the clockwise direction in a circle of radius R = 2.5 m at a given instant of time. The speed of the particle is:
                           

  •   4.5 m/s

  •   5.0 m/s

  •   5.7 m/s

  •   6.2 m/s

A particle moves in space such that

x=2t3+3t+4

y=t2+4t-1

z=2 sin πt

where x, y, z are measured in metres and t in seconds. The acceleration of the particle at t=3s will be

  •   36i^+2j^+k^  ms-2

  •   36i^+2j^+πk^  ms-2

  •   36i^+2j^  ms-2

  •   12i^+2j^  ms-2

The coordinates of a moving particle at a time t, are given by, x = 5sin10t, y = 5cos10t. The speed of the particle is:

  •   25

  •   50

  •   10

  •   502

A particle moves so that its position vector is given by r =cosωt x^+sinωt y^, where ω is a constant. Which of the following is true?
  • Velocity and acceleration both are parallel to r.
  • Velocity is perpendicular to r and acceleration is directed towards to origin.
  • Velocity is parallel to r and acceleration is directed away from the origin.
  • Velocity and acceleration both are perpendicular to r.

Two particles A and B, move with constant velocities v1 and vrespectively. At the initial moment, their position vectors are r1 and r2 respectively. The condition for particles A and B for their collision will be

  •  r1-r2r1-r2=v2-v1v2-v1

  •  r1·v1=r2·v2

  •  r1×v1=r2×v2

  •  r1-r2=v1-v2

The position vector of a particle R as a function of time t is given by 
R=4sin2πti^+4cos2πtj^
Where R is in meters, t is in seconds and i^, j^ denote unit vectors along x and y-directions, respectively. Which one of the following statements is wrong for the motion of the particle?

  • Acceleration is along -R.

  • Magnitude of the acceleration vector is v2R, where v is the velocity of the particle.

  • Magnitude of the velocity of the particle 8 m/s.

  • Path of the particle is a circle of radius 4m.

A bus moves over a straight level road with a constant acceleration a. A body in the bus drops a ball outside. The acceleration of the ball with respect to the bus and the earth are respectively

  • a and g

  • a + g and g - a

  •  a2+g2 and g

  •  a2+g2 and a

The velocity of a projectile at the initial point A is 2i^+3j^m/s. Its velocity (in m/s) at point B is:
            

  • 2i^-3j^

  • 2i^+3j^

  • -2i^+3j^

  • -2i^-3j^

A particle moves in a circle of radius 5 cm with constant speed and time period 0.2π sec. The acceleration of the particle is:

  •   25 m/s2

  •   36 m/s2

  •   5 m/s2

  •   15 m/s2

A missile is fired for a maximum range with an initial velocity of 20 m/s. If g= 10 m/s2, then the range of the missile will be

  •   50 m

  •   60 m

  •   20 m

  •   40 m

A particle has initial velocity (3i^ + 4j^) and has acceleration (0.4i^+ 0.3j^). Its speed after 10 s is

  • 7 units

  • 72units

  • 8.5 units

  • 10 units

A particle of mass m is projected with velocity v making an angle of 45° with the horizontal. When the particle lands on the level ground, the magnitude of change in its momentum will be:

  •   2mv

  •   mv/2

  •   mv2

  •   zero

A particle starting from the origin (0, 0) moves in a straight line in the (x, y) plane. Its coordinates at a later time are (3, 3). The path of the particle makes with the x-axis an angle of:

  • 30o

  • 45o

  • 60o

  • 0o

For a projectile projected at angles (45°-θ) and (45°+θ), the horizontal ranges described by the projectile are in the ratio of:

  • 1:1

  • 2:3

  • 1:2

  • 2:1

A car turns at a constant speed on a circular track of radius 100 m, taking 62.8 s for every circular lap. The average velocity and average speed for each circular lap, respectively, is :

  • 0,0

  • 0, 10 m/s

  • 10 m/s, 10 m/s

  • 10 m/s, 0

The speed of a swimmer in still water is 20 m/s. The speed of river water is 10 m/s and is flowing due east. If he is standing on the south bank and wishes to cross the river along the shortest path, the angle at which he should make his stroke w.r.t north is given by:

  • 45° west of north

  • 30° west of north

  • 0° west of north

  • 60° west of north

Two particles A and B are moving in a uniform circular motion in concentric circles of radii rA and rB with speeds vA and vB respectively. Their time periods of rotation are the same. The ratio of angular speed of A  to that of B will be:

  • 1: 1

  •  rA : rB

  •  vA : vB

  •  rB : rA

A particle starts from rest at t=0 and undergoes an acceleration a in ms-2 with time t in second which is as shown

                   

Which one of the following plot represents velocity v in ms-1 versus time t in second?

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0:0:1


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