CBSE 11TH PHYSICS - Online Test

cbse 11th physics TEST : 42

Units and Measurements Prepare / Learn

Q1.

How many meters does a vehicle moving with a speed of 18 km $h^{- 1}$ covers in 1 s

A. 4

B. 6

C. 5.0

D. 4.5

Answer : Option C
Explaination / Solution:

Speed of vehicle = 18 km h-1

Mean it cover 18 km in 1 hour {3600 seconds)

Distance covered in 3600 sec = 18km = 18000 m

Distance covered in 1 sec = $\frac{18000}{3600} = 5 m$

Oscillations Prepare / Learn

Q2. A spring with spring constant k when stretched through 1 cm has a potential energy U. If it is stretched by 4 cm, the potential energy will become

A. 32U

B. 4U

C. 16U

D. 8U

Answer : Option A
Explaination / Solution:
No Explaination.

Motion in A Straight Line Prepare / Learn

Q3.

The distance (s) in metres travelled by a particle is related to time (t) in seconds by the equation of motion :

S= 10t + 4t2.

What is the initial velocity of the body?

A. 6 m/s

B. 14 m/s

C. 4 m/s

D. 10 m/s

Answer : Option D
Explaination / Solution:

Velocity is given by:

v = $\frac{d s}{d t}$ = $\frac{d (10 t + 4 t^{2})}{d t}$ = $10 + 8 t$

Velocity at t=0, $v_{0} = 10 + 8 \times 0 = 10 m / s$

Waves Prepare / Learn

Q4. A boat at anchor is rocked by waves whose crests are 100 cm apart and whose velocity is 25 cm/sec. These waves reach the boat once every

A. 15 sec

B. 4 sec.

C. 0.25 sec

D. 25 sec.

Answer : Option B
Explaination / Solution:
No Explaination.

Motion in A Plane Prepare / Learn

Q5. A man can swim with a speed of 4.0 km/h in still water. How long does he take to cross a river 1.0 km wide if the river flows steadily at 3.0 km/h and he makes his strokes normal to the river current? How far down the river does he go when he reaches the other bank?

A. 15 min, 750 m

B. 16 min, 650 m

C. 19 min, 500 m

D. 13 min, 700 m

Answer : Option A
Explaination / Solution:

Speed of the man, vm = 4 km/h
Width of the river = 1 km
Time taken to cross the river = $\frac{W i d t h o f t h e r i v e r}{S p e e d o f t h e m a n}$

$= \frac{1}{4} h = \frac{1 \times 60}{4} = 15 min$

Speed of the river, vr = 3 km/h
Distance covered with flow of the river = vr × t
$= \frac{3 \times 1}{4} = \frac{3}{4} k m = \frac{3 \times 1000}{4}$
= 750 m

Mechanical Properties of Solids Prepare / Learn

Q6. Figure shows the strain-stress curve for a given material. What is the approximate yield strength for this material?

A. 3.2

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B. 3.6

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C. 3.0

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108 " role="presentation" style="display: inline; line-height: normal; font-size: 13px; word-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; padding: 0px; margin: 0px; color: rgb(33, 33, 33); font-family: "Open Sans", "Helvetica Neue", Helvetica, Arial, sans-serif; position: relative;"> 108

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D. 3.4

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Answer : Option C
Explaination / Solution:
No Explaination.

Thermodynamics Prepare / Learn

Q7. A cylinder with a movable piston contains 3 moles of hydrogen at standard temperature and pressure. The walls of the cylinder are made of a heat insulator, and the piston is insulated by having a pile of sand on it. By what factor does the pressure of the gas increase if the gas is compressed to half its original volume?

A. 2.64

B. 2.84

C. 3.04

D. 2.44

Answer : Option A
Explaination / Solution:

PVγ=ConstPVγ=Pf(V2)γforH2,γ=1.4Pf=P21.4=2.64P

Laws of Motion Prepare / Learn

Q8. A constant force acting on a body of mass 3.0 kg changes its speed from 2.0 m

s^{- 1}

to 3.5 m

s^{- 1}

in 25 s. The direction of the motion of the body remains unchanged. What is the magnitude and direction of the force?

A. 0.07 m

s^{- 2}

, 0.16 N in the direction of motion

B. 0.08 m

s^{- 2}

, 0.14 N in

C. 0.18 N along the direction of motion

D. 0.09 m

s^{- 2}

, 0.12 N in the direction of motion

Answer : Option C
Explaination / Solution:

$F = m \frac{d v}{d t} = 3 (\frac{3.5 - 2}{25}) = 0.18 N$

Work Energy and Power Prepare / Learn

Q9. Balram exerts a steady force of magnitude F = 200

\hat{i}

+ 2.0

\hat{j}

on the stalled car as shown in the figure above, he pushes it a distance s = 10

\hat{i}

+ 10

\hat{j}

m. How much work does he do?

A. 2320 J

B. 2120 J

C. 2220 J

D. 2020 J

Answer : Option D
Explaination / Solution:

F⃗ =200i^+2

s⃗ =10i^+10

W=F⃗ .s⃗ =(200i^+2j^).(10i^+10j^)

W=2000+20=2020J
jj

Physical World Prepare / Learn

Q10. Technology strives

A. to fulfill a human need such as faster cooking or sewing etc

B. to invent better rat traps

C. to perfect science

D. to use science for application

Answer : Option A
Explaination / Solution:

Science and technology will continue to generate all sorts of new enhancers, and the quest for enhancement is not necessarily unfair or unethical. We humans are inveterate enhancers, striving to increase our intelligence and to improve our memory and powers of perception.

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cbse 11th physics TEST : 42