Physics Test 196

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Physics Test 196

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Question 1
4 / -1

A special kind of ruler can be used to measure reaction time. You position the 'zero' mark between your friend's first finger and thumb. Without warning, you let go of the the rular, and your friend has to grab it as soon as possible. You can read the reaction time from labelled marks on the ruler. The marks, are separated from each other by 0.01 s intervals of falling time. This means that

A
each mark is the same distance from the one before it.

B
the marks get closer together as you go away from the zero.

C
the marks get further apart as you go away from the zero.

D
as you go away from the zero, the marks get closer together then further apart again.
Question 2
4 / -1

An object moves to the East across a frictionless surface with constant speed. A person then applies a constant force to the North on the object. What is the resulting path that the object takes?

A
a straight line path partly Eastward, partly Northward

B
a straight line path totally to the North

C
a parabolic path opening toward the North

D
a parabolic path opening toward the East

Solution

Component of velocity along north will increase
Question 3
4 / -1

An aeroplane is flying vertically upwards. When it is at a height of 1000m above the ground and moving at a speed of 367 m/s., a shot is fired at it with a speed of 567 m/s from a point directly below it. What should be the acceleration of aeroplane so that it may escape from being hit ?

A
>5 m/s²

B
>10 m/s²

C
<10 m/s²

D
Not possible

Solution

0 = (200)² – 2(arel) (1000)

or a_rel = 20 m/s²

So to avoit the hit,

a_rel > 20 m/s²

or a_p > 10 m/s²
Question 4
4 / -1

A jet plane flying at a constant velocity V at a height h = 8 km is being tracked by a radar R located at O directly below the line of flight. If the angle θ is decreasing at the rate of 0.025 rad/s., when θ = 60° the velocity of the plane is :

A
1440 km/h

B
960 km/h

C
1920 km/h

D
480 km/h

Solution
Question 5
4 / -1

The figure Shows the acceleration of a particle versus time graph. The particle starts from rest at t = 0. Find the approximate velocity at t = 1s.

A
0.9 m/s

B
1.6 m/s

C
3.6 m/s

D
0.1 m/s

Solution

Counting the squares under the graph from t = 0 to t = 1. We get change in velocity.
Question 6
4 / -1

A uniform rope of length L and mass M is placed on a smooth fixed wedge as shown. Both ends of rope are at same horizontal level.The rope is initially released from rest, then the magnitude of initial acceleration of rope is

A
Zero

B
M(cos α – cos β)g

C
M(tan α - tan β)

D
None of these

Solution
Question 7
4 / -1

Figure shows two 45° wedges, the smaller wedge w has a horizontal top face. It can slide down the larger wedge W, which is on a horizontal table. All the surfaces are smooth. A mass m sits on the top face of the upper wedge.

Describe qualitatively the motion of the system once it is released from rest.

A

B

C

D
Question 8
4 / -1

A block of mass m is kept on a rough inclined plane with coefficient of friction µ. The force required to just move the block up is

A
µmg cos θ

B
mg sin θ

C
mg sin θ + µmg cos θ

D
mg sin θ – µ mg cos θ

Solution
Question 9
4 / -1

Directions For Questions

The variation of the vertical speed with time of a ball falling in air is shown below.

During the time from 0 to T, the ball gains kinetic energy and loses gravitational potential energy ΔE_P.

...view full instructions

Which of the following statements must be correct?

A
ΔE_P is equal to the gain in kinetic energy

B
ΔE_P is equal to the work done against air resistance

C
ΔE_P is greater than the gain in kinetic energy

D
ΔE_P is less than the work done against air resistance

Solution
Question 10
4 / -1

One end of a light rope is tied directly to the ceiling. A man initially at rest on the ground starts climbing the rope hand over hand upto a height ℓ.

From the time he starts at rest on the ground to the time he is hanging at rest at a height ℓ, how much work was done on the man by the rope?

A
0

B
Mgℓ

C
– Mgℓ

D
It depends on how fast the man goes up.

Solution

This is subtle, because it is the force that the rope applies to the man that causes him to move upward, against the force of gravity. Nonetheless, as he climbs hand over hand, the hand that is holding the rope is always stationary, while man's body and his free hand move upward. Since the force of the rope is applied to the man's stationary hand, there is no displacement of the object to which the force is applied, and hence no work done.