Physics Test 3

Result

Physics Test 3

Score
-
out of -
Rank
-
out of -

TIME Taken - -

SHARING IS CARING

If our Website helped you a little, then kindly spread our voice using Social Networks. Spread our word to your readers, friends, teachers, students & all those close ones who deserve to know what you know now.

Weekly Quiz Competition

Question 1
4 / -1

Due to the superposition of the certain number of waves, the equation of the particle at a point is given by z= 40sin²(100t)*cos(50t)sin(50t). Find the number of waves superimposed in the given wave equation.

A
3

B
4

C
5

D
2

Solution

z= 40sin²(100t)*cos²(100t)

= 10(1-cos(50t))*sin(100t)

= 10sin(100t)-10sin(100t)cos(50t)

= 10sin(100t)- 10(sin(75t)-sin(25t))

= 10sin(100t) – 10sin(75t) + 10sin(25t)

Hence, 3 waves are superimposed.
Question 2
4 / -1

A block of mass 5 kg is dropped from a height of 5 m over a board which is supported by two parallel and same springs of spring constant 100 N/m. Find the work done by each spring when the block comes to rest. (Take g= 10 m/s²)

A
-156.25 J

B
+39.07 J

C
-78.125 J

D
+156.25 J

Solution

Velocity of the block when it hits the board= √2*10*5= 10 m/s

Using work energy principle,

KE_final – KE_initial= W_gravity +W_springs

Springs are parallel with equal spring constants, Hence two springs can be replaced by a spring with k= 200 N/m

Now,

KE_final= 0 ... (when block comes to rest)

0 - KE_initial= -mgH – 1/2 k*H²

-1/2 5*10²= -10*10*H – 0.5*200*H

H= 1.25 m

Therefore, work done by each spring= -1/2 *100*(1.25)²= -78.125 J
Question 3
4 / -1

In the first case, a spring is pulled by 10 cm while in the second case, four springs are attached in parallel and pulled simultaneously. By what distance, should the four springs be pulled to get energies stored in them, in total, equal to the energy stored in the spring from the first case?

A
2.5 cm

B
40 cm

C
3.33 cm

D
5 cm

Solution

For single spring,

Energy= 1/2 *k*(10)²= 50k

For three spring,

Keq= k+k+k+k= 4k

Energy= 1/2 *(4k)*x²= 50k

x= 5 cm
Question 4
4 / -1

Which one of the following statements is true?

A
Most accurate measurement has low error.

B
Most precise measurement has low error

C
Most accurate measurement has high error.

D
Most precise measurement has high error.

Solution

We cannot tell anything about the error from a precise measurement.

Accurate measurements have less error. But it is possible that there is a greater standard deviation. But of course, the errors are much lower.
Question 5
4 / -1

If mass of proton= 1.008 amu and mass of neutron= 1.009 amu, then the binding energy per nucleon for ₁₂C⁶ (mass= 12.0107 amu ) is,

A
6.1 MeV

B
14.3 MeV

C
7.1 MeV

D
10.3 Mev

Solution

B.E. (MeV)= mass defect *931.5 /Atomic no.

Mass defect= (1.008*6 + 1.009*6 -12.0107)= 0.0913amu

B.E.= 0.0913* 931.5 /12= 7.1 MeV
Question 6
4 / -1

Which of the following is true?

A
Photoelectric effect depicts wave-nature of light.

B
Kinetic Energy of emitted electron increases as work function increases for a particular incident photon.

C
There is a limit to Kinetic Energy of the emitted electron for a set of particular incident photon and the metal surface.

D
Work function depends also on the incident photon.

Solution

The work function is the property of a particular metal surface and is constant for a particular metal.

Photoelectric effect directly depicts particle nature of light since it is photon-electron interaction.

For a particular incident photo and a metal surface, maximum KE of emitted electrons is fixed. It cannot be more than a certain limit.
Question 7
4 / -1

If the frequency of 4*10¹⁴Hz is incident on a metal surface, find the work function of the metal. Take the stopping potential as 1 eV.

A
2.66 eV

B
0.66 eV

C
2.32 eV

D
1.66 eV

Solution

hν= φ + eVo ...... (eVo =stopping potential)

Substituting the values,

φ= 0.66 eV
Question 8
4 / -1

Which of the following is not true?

A
De-Broglie hypothesis supports wave nature of light.

B
Diffraction and interference are causes of wave nature of light.

C
According to De-Broglie hypothesis, the wavelength is inversely proportional to momentum.

D
According to De-Broglie hypothesis, wavelength is directly proportional to mass of the particle.

Solution

All the other options are either statements or consequences of De-Broglie hypothesis.

Wavelength is inversely proportional to mass.

User

Question Analysis

Correct -
Wrong -
Skipped -

My Perfomance

Score
-
out of -
Rank
-
out of -

Re-Attempt Weekly Quiz Competition

Physics Test 3

Result

Physics Test 3

Score

-

Rank

-

SHARING IS CARING

Question 1

3

4

5

2

Solution

Question 2

-156.25 J

+39.07 J

-78.125 J

+156.25 J

Solution

Question 3

2.5 cm

40 cm

3.33 cm

5 cm

Solution

Question 4

Most accurate measurement has low error.

Most precise measurement has low error

Most accurate measurement has high error.

Most precise measurement has high error.

Solution

Question 5

6.1 MeV

14.3 MeV

7.1 MeV

10.3 Mev

Solution

Question 6

Photoelectric effect depicts wave-nature of light.

Kinetic Energy of emitted electron increases as work function increases for a particular incident photon.

There is a limit to Kinetic Energy of the emitted electron for a set of particular incident photon and the metal surface.

Work function depends also on the incident photon.

Solution

Question 7

2.66 eV

0.66 eV

2.32 eV

1.66 eV

Solution

Question 8

De-Broglie hypothesis supports wave nature of light.

Diffraction and interference are causes of wave nature of light.

According to De-Broglie hypothesis, the wavelength is inversely proportional to momentum.

According to De-Broglie hypothesis, wavelength is directly proportional to mass of the particle.

Solution

User

Question Analysis

My Perfomance

Score

-

Rank

-

Results Announcement on: coming Monday

Stay Tuned: We’ll update you on your result via email or SMS.