Physics Test 181

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Physics Test 181

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Question 1
4 / -1

The damping force on an oscillator is directly proportional to the velocity. The units of the constant of proportionality are

A
kgms⁻¹

B
kgms⁻²

C
kgs⁻¹

D
kg s

Solution
Question 2
4 / -1

The density of a material in CGS system of units is 4g∕cm³ In a system of units in which unit of length is 10 cm and unit of mass is 100 g, the value of density of material will be

A
0.04

B
0.4

C
40

D
400

Solution
Question 3
4 / -1

A student measures the distance traversed in free fall of a body, initially at rest, in a given time. He uses this data to estimate g, the acceleration due to gravity. If the maximum percentage errors in measurement of the distance and the time are e₁ and e₂ respectively, the percentage error in the estimation of g is

A
e₂ − e₁

B
e₁ + 2e₂

C
e₁ + e₂

D
e₁ − 2e₂

Solution
Question 4
4 / -1

If the error in the measurement of radius of a sphere is 2%, then the error in the determination of volume of the sphere will be

A
8%

B
2%

C
4%

D
6%

Solution

Error in the determination of the volume = 3×2% = 6%
Question 5
4 / -1

Dimensions of resistance in an electrical circuit, in terms of dimension of mass M, of length L, of time T and of current I, would be

A
[M L²T⁻²]

B
[M L²T⁻¹I⁻¹]

C
[M L²T⁻³I⁻²]

D
[M L²T⁻³I⁻¹].

Solution
Question 6
4 / -1

The ratio of the distances travelled by a freely falling body in the 1st ,2nd ,3rd and 4th second

A
1 : 2 : 3 : 4

B
1 : 4 : 9 : 16

C
1 : 3 : 5 : 7

D
1 : 1 : 1 : 1

Solution
Question 7
4 / -1

The position-time (x–t) graph for positive acceleration is :

A

B

C

D

Solution
Question 8
4 / -1

A car starts from rest and accelerates at 5 m/s². At t = 4 s, a ball is dropped out of a window by a person sitting in the car. What is the velocity and acceleration of the ball at t = 6 s?(Take g = 10 m/s²)

A
20 m/s, 5 m/s²

B
20 m/s, 0

C
20√2 m/s, 0

D
20√2 m/s, 10 m/s²

Solution

Initial velocity of car = 0

Acceleration of car = 5 m/s²

Velocity of car at t = 4 s; v = u + at

⇒ v = 0 + 5 × 4 = 20 ms^–1At t = 4 s, A ball is dropped out of a window so velocity of ball at this instant is 20 ms–1 along horizontal.

After 2 seconds of motion :

Horizontal velocity of ball = 20ms⁻¹(∵ a_x = 0)

Vertical velocity of ball (v_y) = u_y + a_yt

v_y= 0 + 10 × 2 = 20ms⁻¹ (∵ ay = g = 10m∕s²)

So magnitude of velocity of ball

Acceleration of ball at t = 6s is g = 10m∕s²

As ball is under free fall.
Question 9
4 / -1

Preeti reached the metro station and found that the escalator was not working. She walked up the stationary escalator in time t₁. On other days, if she remains stationary on the moving escalator, then the escalator takes her up in time t₂. The time taken by her to walk up on the moving escalator will be

A

B

C
t₁ − t₂

D

Solution

Let v₁ is the velocity of preeti on stationary escalator and d is the distance travelled by her
Question 10
4 / -1

Two cars P and Q start from a point at the same time in a straight line and their positions are represented by x_p(t) = (at + bt²) and x_Q(t) = (ft − t²). At what time do the cars have the same velocity?

A

B

C

D

Solution