﻿ Engineering Entrance Exam Question and Answers | Motion in A Plane - Zigya

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# Motion in A Plane

#### Multiple Choice Questions

1.

A particle is moving eastwards with a velocity of 5 m/s in 10 seconds the velocity changes to 5 m/s northwards. The average acceleration in this time is

• towards north-east
• towards north.
• zero

• towards north-west

D. towards north-west  199 Views

2.

A car starting from rest accelerates at the rate f through a distance S, then continues at constant speed for time t and then decelerates at the rate f/2 to come to rest. If the total distance traversed is 15 S, then

• S=ft

• S= ft2/72

• S = 1/2 ft2

• S = 1/4 ft2

B.

S= ft2/72  275 Views

3. then the angle between A and B isπ
• π

• π/3

• π/2

• π/4

A.

π 163 Views

4.

The relation between time t and distance x is t=ax2 +bx where a and b are constants. The acceleration is

• −2abv2

• 2bv3

• −2av3

• 2av2

C.

−2av3

if t = ax2+bx
then, differentiate both side with respect to time (t)

Again differentiate both side with respect to time (t)
Hence, retardation= -2av3

5.

Which of the following statements is false for a particle moving in a circle with a constant angular speed?

• The velocity vector is tangent to the circle.

• The acceleration vector is tangent to the circle.

• The acceleration vector points to the centre of the circle.

• The velocity and acceleration vectors are perpendicular to each other.

B.

The acceleration vector is tangent to the circle.

For a particle moving in a circle with constant angular speed, the velocity vector is always tangent to the circle and the acceleration vector always points towards the centre of the circle or is always along the radius of the circle. Since, the tangential vector is perpendicular to radial vector, therefore, velocity vector will be perpendicular to the acceleration vector. But in no case acceleration vector is tangent to the circle.
165 Views

6.

A particle is acted upon by a force of constant magnitude which is always perpendicular to the velocity of the particle, the motion of the particle takes place in a plane. It follows that

• its velocity is constant

• its acceleration is constant

• its kinetic energy is constant

• it moves in a straight line.

C.

its kinetic energy is constant

When a force of constant magnitude acts on the velocity of particle perpendicularly, then there is no change in the kinetic energy of the particle. Hence, kinetic energy remains constant.

188 Views

7.

A parachutist after bailing outfalls 50 m without friction. When a parachute opens, it decelerates at 2 m/s2. He reaches the ground with a speed of 3 m/s. At what height, did he bail out?

• 91 m

• 182 m

• 293 m

• 111 m

C.

293 m 142 Views

8.

A projectile can have the same range R for two angles of projection. If t1 and t2 be the times of flights in the two cases, then the product of the two time of flights is proportional to

• R2

• 1/R2

• 1/R

• R

D.

R 251 Views

9.

A projectile can have the same range R for two angles of projection. If T1 and T2 be the time of flights in the two cases, then the product of the two time of flights is directly proportional to

• 1/R2

• 1/R

• R

• R2

C.

R

We know in advance that range of projectile is same for complementary angles i.e. for θ and (900 - θ ) 271 Views

10.

A body of mass m accelerates uniformly from rest to v1 in time t1. The instantaneous power delivered to the body as a function of time t is

• • • • B. Let the constant acceleration of body of mass m is a.
From equation of motion

v1 = 0 + at1
⇒ a = t2/t= ...... (i)
At an instant t, the velocity v of the body v = 0 + at 515 Views