Physics Test 79

Result

Physics Test 79

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

A block of mass 2kg is suspended by a light string from the ceiling of a lift. The lift starts moving down with an acceleration a = 1.8 m/s². Find the work done by tension in the string during the first 5 seconds.

A
360 J

B
–360 J

C
180 J

D
–144 J

Solution
Question 2
4 / -1

A bullet moving with a speed of 100 m/sec travels a distance of 2cm in a plank of wood before coming to rest. How much distance will the same bullet travel in the same plank before coming to rest if it were moving with a speed of 200 m/sec ?

A
8 cm

B
2 cm

C
4 m

D
16 cm

Solution
Question 3
4 / -1

A mass m, lying on a horizontal frictionless surface is connected to a mass M as shown in figure. The system is now released. The velocity of mass m when mass M discends a distance h is

A

B

C

D

Solution
Question 4
4 / -1

A body of mass 5 kg rests on a rough horizontal surface of coefficient of friction 0.2. The body is pulled through a distance of 10m by a horizontal force of 25N. The kinetic energy acquired by it is (g = 10 m/s²)

A
100 J

B
150 J

C
250 J

D
200 J

Solution

Friction force = μmg = 0.2 × 5 × 10 = 10N
Net force F = 25 – 10 = 15N
Kinetic energy = work done by net force
KE = FS cos 0° = 15 × 10 = 150 J
Question 5
4 / -1

A particle is released from rest at origin. It moves under the influence of potential field U = x² – 3x. Kinetic energy of particle at x = 2 is

A
2 J

B
1 J

C
1.5 J

D
0 J

Solution

At x =0, U = 0, KE = 0
thus total energy of particle = 0
at x = 2, U = x² – 3x
U = (2)²– 3(2) = –2J
KE + PE = 0
KE – 2 = 0
KE = 2J
Question 6
4 / -1

A block begins to move on a rough horizontal surface with an initial velocity 'u'. If it loses 1/4 of its initial kinetic energy in time 't', the coefficient of kinetic friction between the block and the surface is

A

B

C

D

Solution
Question 7
4 / -1

Kinetic energy of a particle moving in a straight line varies with time t as K = 4t². The force acting on the particle

A
is constant

B
is increasing

C
is decreasing

D
first increases and then decrease

Solution
Question 8
4 / -1

A particle is projected with a velocity u making an angle θ with the horizontal. The instantaneous power of the gravitational force

A
varies linearly with time

B
is constant throughout

C
is negative for complete path

D
zero
Question 9
4 / -1

Force where x in meter, acts on a particle. Work done on the particle as it moves from coordinates (2m, 3m) to (3m, 0m) is

A
3J

B
5J

C
7J

D
zero

Solution
Question 10
4 / -1

In the diagram shown all surfaces are smooth. If the system is released from rest with spring un stretched. Then the maximum extension in the spring will be

A

B

C

D

Solution

At maximum elongation velocity of both the blocks is zero
by work – energy the theorem