Physics Test 180

Result

Physics Test 180

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Weekly Quiz Competition

Question 1
4 / -1

Plane angle and solid angle have

A
Units but no dimensions

B
Dimensions but no units

C
No units and no dimensions

D
Both units and dimensions

Solution
Question 2
4 / -1

The physical quantity that has the same dimensional formula as pressure is:

A
Coefficient of viscosity

B
Force

C
Momentum

D
Young's modulus of elasticity

Solution
Question 3
4 / -1

If force [F], acceleration [A] and time [T] are chosen as the fundamental physical quantities. Find the dimensions of energy.

A
[F][A][T]

B
[F][A][T²]

C
[F][A][T⁻¹]

D
[F][A⁻¹][T]

Solution

Energy, E ∝ F^aA^bT^c

[E] = [F^a][A^b][T^c]

⇒ [ML²T⁻²] = [MLT⁻²]^a[LT⁻²]^b[T]^c

[ML²T⁻²] = [M^aL^a+bT^−2a−2b+c]

Comparing dimensions on both sides.

⇒ a = 1 ; a + b = 2 and −2 = −2a − 2b + c

⇒ b = 1 ⇒ −2 = −2 −2 + c

⇒ c = 2

[E] = [F AT²]
Question 4
4 / -1

If E and G respectively denote energy and gravitational constant, then E/G has the dimensions of

A
[M²][L⁻¹][T⁰]

B
[M][L⁻¹][T⁻¹]

C
[M][L⁰][T⁰]

D
[M²][L⁻²][T⁻¹]

Solution
Question 5
4 / -1

Taking into account of the significant figures, what is the value of 9.99m − 0.0099m?

A
9.98m

B
9.980m

C
9.9m

D
9.9801m

Solution

In subtraction the number of decimal places in the result should be equal to the number of decimal places of that term in the operation which contain lesser number of decimal places.

9.99 − 0.0099 = 9.9801

As the least number of decimal places is 3.

So, answer should be 9.98m.
Question 6
4 / -1

The unit of thermal conductivity is.

A
W m⁻¹K⁻¹

B
J mK⁻¹

C
J m⁻¹K⁻¹

D
W mK⁻¹

Solution

where Q is the amount of heat flow, x is the thickness of the slab, A is the area of cross-section, and t is the time taken.
Question 7
4 / -1

The main scale of a vernier callipers has n divisions/cm. n divisions of the vernier scale coincide with (n-1) divisions of main scale. The least count of the vernier callipers is,

A

B

C

D

Solution

If n^th division of vernier scale coincides with (n − 1) divisions of main scale.

Therefore, nV SD = (n − 1)MSD
Question 8
4 / -1

A physical quantity of the dimensions of length that can be formed out of c, G and is [c is velocity of light, G is the universal constant of gravitation and e is charge].

A

B

C

D

Solution
Question 9
4 / -1

If dimensions of critical velocity v_c of a liquid flowing through a tube are expressed as [η^xρ^yγ^z] where η, ρ and γ are the coefficient of viscosity of liquid, density of liquid and radius of the tube respectively, then the values of x, y and z are given by.

A
-1,-1,-1

B
1,1,1

C
1,-1,-1

D
-1,-1,1

Solution

[v_c] = [η^xρ^yγ^z] (given) ........(i)

Writing the dimensions of various quantities in eqn. (i), we get

[M⁰LT⁻¹] = [M L⁻¹T⁻¹]^x[M L⁻³T⁰]^y[M⁰LT⁰]^z

= [M^x+yL^−x−3y+zT^−x]

Applying the principle of homogeneity of dimensions, we get

x + y = 0; −x − 3y + z = 1; −x = −1

On solving, we get x = 1, y = −1, z = −1
Question 10
4 / -1

In an experiment four quantities a, b, c and d are measured with percentage error 1%, 2%, 3% and 4% respectively. Quantity P is calculated as follows

A
7%

B
4%

C
14%

D
10%

Solution