Physics Test 2

Result

Physics Test 2

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

If a block of mass M is floating on the water (ρw= 1000 kg/m³) with 100 cm³ volume such that 1/4^th of the volume of the block is immersed in water. Find the mass of another block placed over this block such that lower block just gets immersed completely.

A
100 g

B
25 g

C
75 g

D
50 g

Solution

When initially 1/4^th volume is immersed, writing the force equation in Y-direction;

V*ρ_block*g= V/4 * ρw * g... (V is volume of block)

From this,

ρ_block= ρw/4

When another block is placed such that the lower block just gets fully immersed,

mg+ V*ρ_block*g= V * ρw * g

from this,

m= ( ¾)* V* ρw= 0.075 kg=75 g
Question 2
4 / -1

What is not true regarding Reynold’s number?

A
For low Reynold’s number, viscous forces are dominant

B
Reynold’s number is directly proportional to kinematic viscosity.

C
Reynold’s number is directly proportional to density.

D
Reynold’s number is high when eddies are present.

Solution

Reynold’s number is inversely proportional to kinematic viscosity. Because of lesser the viscosity, higher are the chances of flow being turbulent. Or flow with high-Reynold’s number.
Question 3
4 / -1

A 70kg man, standing on the bank of the river, suddenly jumps in a boat with mass 10kg and going with speed 10m/s (X-direction) downstream, perpendicular to its motion. The velocity of man while jumping is 2m/s (Y-direction). Find the final velocity with direction. Assume the velocities of the man (y-axis) and the boat (x-axis) are pointing in the positive direction initially.

A
Vfx= -1.75 m/s and Vfy= 1.25 m/s

B
Vfx= 1.75 m/s and Vfy= -1.25 m/s

C
Vfx= -1.25 m/s and Vfy= 1.75 m/s

D
Vfx= 1.25 m/s and Vfy= 1.75 m/s

Solution

Momentum conservation in X-axis,

Pi= Pf

M_man* 0 +M_boat*10 = (M_man + M_boat) * Vfx

Vfx= 1.25 m/s

Momentum conservation in Y-axis,

Pi= Pf

M_man*2 + M_boat*0 = (M_man+M_boat) * Vfy

Vfy= 1.75 m/s
Question 4
4 / -1

The upstream velocity of a boat is 2m/s and downstream velocity is 20m/s and distance between two points is 500m. What is the time required by the boat to go upstream if the river is flowing with half of the original speed?

A
500 sec

B
111 sec

C
77 sec

D
55 sec

Solution

For Upstream,

V_boat – V_river= V_upstream= 2 m/s ......(1)

For downstream,

V_boat + V_river= V_downstream= 20 m/s .....(2)

From eq.(1) and (2),

V_boat= 11 m/s and V_river= 9 m/s

Given if V_river(new)= 9/2= 4.5 m/s

Therefore,

V_upstream= V_boat – V_river(new)= 11 - 4.5= 6.5 m/s

Therefore, time required to go upstream= 500/6.5≈ 77 sec
Question 5
4 / -1

Which of the following is true?

A
Periodic motion is always an oscillatory motion.

B
The oscillatory motion may or may not be a periodic motion.

C
In the periodic motion, the object moves to and fro.

D
The object moves to and fro about a point in oscillatory motion.

Solution

Periodic motion has nothing to do with the path of the object whereas oscillatory motion is always periodic in nature.
In the oscillatory motion, there is to and fro displacement of the body about a fixed point.
Question 6
4 / -1

For a particle performing SHM, if the maximum velocity of the particle is made 4 times, which one of the following is true?

A
Frequency will become 4 times

B
Amplitude will becomes 4 times

C
Period will become 2 times

D
Maximum acceleration will become 8 times.

Solution

Since, frequency depends on the mass and spring constant, frequency and time period won’t change.

Vmax = Aω

If Vmax is made 4 times, and frequency is constant amplitude will become 4 times.

Amax = Aω²

So frequency is constant, maximum acceleration only depends on amplitude. Hence it will become 4 times, not 8 times.
Question 7
4 / -1

If two balls, 2 kg and 5 kg, are separated such that their center of mass lies at the origin. If the 2 kg ball starts moving at velocity 5 m/s to the left and the 5 kg ball starts moving right with velocity 1 m/s, find the velocity and position of the center of mass after 4 sec.

A
0.72 m/s and 2.88 m

B
2.15 m/s and 8.6 m

C
-0.72 m/s and -2.88 m

D
-2.15 m/s and -8.6 m

Solution

M_total*Vcm= M₁*V₁ + M₂*V₂

V₁= -5m/s and V₂= +1 m/s

Substituting the values,

(2+5)*Vcm= 2*(-5)+5*(1) =-5

Vcm= -0.72 m/s

Xcm= Vcm * t= -0.72*4= -2.88 m

User

Question Analysis

Correct -
Wrong -
Skipped -

My Perfomance

Score
-
out of -
Rank
-
out of -

Re-Attempt Weekly Quiz Competition

Physics Test 2

Result

Physics Test 2

Score

-

Rank

-

SHARING IS CARING

Question 1

100 g

25 g

75 g

50 g

Solution

Question 2

For low Reynold’s number, viscous forces are dominant

Reynold’s number is directly proportional to kinematic viscosity.

Reynold’s number is directly proportional to density.

Reynold’s number is high when eddies are present.

Solution

Question 3

Vfx= -1.75 m/s and Vfy= 1.25 m/s

Vfx= 1.75 m/s and Vfy= -1.25 m/s

Vfx= -1.25 m/s and Vfy= 1.75 m/s

Vfx= 1.25 m/s and Vfy= 1.75 m/s

Solution

Question 4

500 sec

111 sec

77 sec

55 sec

Solution

Question 5

Periodic motion is always an oscillatory motion.

The oscillatory motion may or may not be a periodic motion.

In the periodic motion, the object moves to and fro.

The object moves to and fro about a point in oscillatory motion.

Solution

Question 6

Frequency will become 4 times

Amplitude will becomes 4 times

Period will become 2 times

Maximum acceleration will become 8 times.

Solution

Question 7

0.72 m/s and 2.88 m

2.15 m/s and 8.6 m

-0.72 m/s and -2.88 m

-2.15 m/s and -8.6 m

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.