Physics Test 63

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Physics Test 63

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Weekly Quiz Competition

Question 1
1 / -1

A body rolls down an inclined plane. If its kinetic energy of rotation is 40% of its kinetic energy of translation, the body is a

A
Solid cylinder

B
Solid sphere

C
Disc

D
Ring

Solution
Question 2
1 / -1

Displacement y (in m) of a body varies with time t (in sec) as: y=−2/3 t²+16t+2. How long does the body take to come to rest?

A
8 sec

B
10 sec

C
12 sec

D
16 sec

Solution

The displacement is given as:

y=ut+1/2at²

where, u is the initial velocity and a is the acceleration.

Comparing with given expression:

y=16t − 2t²/3 + 2,

We get,

u=16 m/s, and a=−4/3 m/s²

As, v=u+at, where v is final velocity.

Taking v=0, the time taken for body to come to rest. 0=16−4/3 t

⇒t=12sec

Hence, the correct option is (C).
Question 3
1 / -1

The velocity-time graph of a moving train is depicted in the figure below. The average velocity during time OD was

A
30 m/s

B
60 m/s

C
45 m/s

D
23 m/s

Solution

The velocity-time graph of a moving train is depicted in the question figure. The average velocity during time OD was 30 m/s by the formula,

i.e., v=d/t

Hence, the correct option is (A).
Question 4
1 / -1

An open U-tube contains mercury. When 11.2 cm of water is poured into one of the arms of the tube, how high does the mercury rise in the other arm from its initial level?

A
0.56 cm

B
1.35 cm

C
0.41 cm

D
2.32 cm

Solution

At the same level in the two limbs of a U-tube, the pressure is the same. On pouring water on the left side, mercury rises x cm (say) from its previous level in the right limb of the U-tube

creating a difference of levels of mercury by 2x cm.

Equating pressures at A and B, we get
Question 5
1 / -1

Waterfalls from a height of 500 m. What is the rise in temperature of water at the bottom if whole energy remains in the water?

A
0.96⁰ C

B
1.02⁰ C

C
1.16⁰ C

D
0.23⁰ C

Solution

Water is at height (h)=500 m

Potential energy =mgh

=1×9.81×500

=4905 J/ litre

Specific heat of water =4180 J/kg

So,E=mcΔT

4905=1×4180×ΔT

ΔT=4905/4180

ΔT=1.16^∘C

Hence, the correct option is (C).
Question 6
1 / -1

Two vibrating strings of the same material, but lengths L and 2 L have radii 2 r and r, respectively. They are stretched under the same tension. Both the strings vibrate in their fundamental modes, the one of length L with frequency v₁ and the other with frequency v₂. The ratio v₁/v₂ is

A
2

B
4

C
8

D
1

Solution
Question 7
1 / -1

A uniform cylindrical rod of mass m and length L is rotating with an angular velocity ω. The axis of rotation is perpendicular to its axis of symmetry and passes through one of its edges faces. If the room temperature increases by t and the coefficient of linear expansion is α, the change in its angular velocity is :

A
√ω

B
2ωat

C
ω²

D
1/ω

Solution
Question 8
1 / -1

A circular coil of radius R carries an electric current. The magnetic field due to the coil at a point on the axis of the coil located at a distance r from the centre of the coil, such that r>>R, varies as

A
1/r

B
1/r^3/2

C
1/r²

D
1/r³

Solution
Question 9
1 / -1

In Young's double slit experiment the 10^th maximum, of wavelength λ₁ is at a distance of y₁ from the central maximum. When the wavelength of the source is changed to λ₂,5^th maximum is at a distance of y2 from its central maximum. The ratio y₁/ y₂

A
2λ₁/ λ₂

B
2λ₂/ λ₂

C
λ₁/ 2λ₂

D
λ₂/2λ₁

Solution
Question 10
1 / -1

The ratio of the wavelengths of the longest wavelength lines in Lyman and Balmer series of hydrogen spectrum is

A
3/23

B
5/27

C
7/29

D
9/31

Solution