Physics Test

Result

Physics Test - 21

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Question 1
3 / -1

The excess pressure inside a spherical drop of water is four times that of another drop. Then, their mass ratio is

A
1 : 16

B
8 : 1

C
1 : 4

D
1 : 64

Solution
Question 2
3 / -1

A balloon starts rising from the ground with an acceleration of 1.25 m/s2. After 8 s, a stone is released from the balloon. The stone will, after release from the balloon,

A
cover a distance of 40 m

B
have a displacement of 50 m

C
reach the ground in 4 s

D
begin to move down

Solution
Question 3
3 / -1

A particle in SHM is described by the displacement equation x(t) = A cos (ωt + θ). If the initial (t = 0) position of the particle is 1 cm and its initial velocity is π cm/s, then what is its amplitude? (The angular frequency of the particle is πs^-1.)

A
1 cm

B
√2 cm

C
2 cm

D
2.5 cm

Solution
Question 4
3 / -1

From the top of a tower, a stone is thrown up and reaches the ground in time t₁ = 9 s. A second stone is thrown down with the same speed and reaches the ground in time t₂ = 4 s. A third stone is released from rest and reaches the ground in time t₃, which is equal to

A
6.5 s

B
6 s

C
65 s

D
64 s

Solution
Question 5
3 / -1

Two balls marked 1 and 2 of the same mass m and a third ball marked 3 of mass M are arranged over a smooth horizontal surface as shown in the figure. Ball 1 moves with a velocity v₁toward balls 2 and 3. All collisions are assumed to be elastic. If M < m, the number of collisions between the balls will be

A
one

B
two

C
three

D
four

Solution
Question 6
3 / -1

A spring of force constant k is cut into two pieces such that one piece is double the length of the other. The force constant of the longer piece will be

A
1.5k

B
3k

C
2k

D
2/3k

Solution
Question 7
3 / -1

A particle has an initial velocity of 9 m/s due east and a constant acceleration of 2 m/s2 due west. The distance covered by the particle in the fifth second of its motion is

A
0 m

B
0.5 m

C
2 m

D
None of these

Solution

The displacement is indeed 0 but not the distance. the distance covered is 0.5 m.

Actually, the car is changing the direction of motion at 4.5 seconds. As such displacement between 4 and 5 seconds is 0 but still the car covers some distance.

The distance is the mod of displacement made by the car between 4 and 4.5 seconds + mod of the displacement between 4.5 and 5 seconds.

Displacement b/w 4 to 4.5 seconds = (9)(0.5) - (4.5² - 4²) = 4.5 - 4.25 = 0.25

Displacement b/w 4.5 to 4 seconds = (9)(0.5) - (5² - 4.5²) = 4.5 - 4.75 = -0.25

Displacement = 0, Distance = 0.5 m
Question 8
3 / -1

A block released on a rough inclined plane of inclination = 30° slides down the plane with an acceleration g/4, where g is the acceleration due to gravity. What is the coefficient of friction between the block and the inclined plane?

A
2/√3

B
1/√3

C
1/2√3

D
√3/2

Solution
Question 9
3 / -1

A boy, while catching a ball, experiences an impulse of 6 Ns. If the mass of the ball is 200 g, then what was the speed of the ball before it was caught?

A
10 ms^-1

B
30 ms^-1

C
20 ms^-1

D
40 ms^-1

Solution
Question 10
3 / -1

The angular velocity of a planet revolving in an elliptical orbit around the sun __________ when it comes near the sun

A
decreases

B
increases

C
remains the same

D
None of these

Solution