# Physical World And Measurement MCQs

Physical-world and measurement is understanding the fundamental forces and other physical parameters. There are four fundamental forces and they are:

• Gravitational force
• Nuclear force
• Weak force
• Electromagnetic force

The physical parameters also known as physical quantities are used for expressing all the laws of Physics. These quantities are

• Fundamental quantities
• Derived quantities

The above-mentioned quantities are expressed using the system of units and they are:

• MKS (metre, kilogram, second)
• CGS (centimetre, gram, second)
• FPS (foot, pound, second)
• SI (International System of Units

1.How many numbers of base SI units are there?

(a) 5

(b) 10

(c) 7

(d) 9

2. What is the percentage error in the measurement of the kinetic energy of a body, if there is a positive error of 50% in the speed of the body

(a) 125%

(b) 30%

(c) 50%

(d) 100%

3. What is the dimensional formula of torque and energy

(a) [ML-3T-2] and [MLT-2]

(b) [ML2T-2] and [MLT-2]

(c) [ML2T-2] and [ML2T2]

(d) [MLT2] and [ML2T2]

4. Find the relative error of y, if y=x2(a) $\frac{\bigtriangleup x}{x}$

(b) $\frac{2\bigtriangleup x}{x}$

(c) $\frac{(\bigtriangleup x)^{2}}{x}$

(d) $(\bigtriangleup x)^{2}$

Answer: (b) $\frac{2\bigtriangleup x}{x}$

5. Identify the physical parameters that are having the same dimensions from the below-given list:

(i) Magnetic field

(ii) Energy density

(iii) Refractive index

(iv) Young’s modulus

(v) Dielectric constant

(a) (ii) and (iv)

(b) (i) and (v)

(c) (iii) and (iv)

(d) (iv) and (iii)

6. What is the angle between A and B, ifÂ $\vec{A}+\vec{B}=\vec{C}$ such thatÂ $\vec{C}$ is perpendicular toÂ $\vec{A}$ andÂ $\left | \vec{A} \right |=\left | \vec{C} \right |$

(a) Ï€

(b) $\frac{\pi }{2}$

(c)$\frac{\pi }{4}$

(d) $\frac{3\pi }{4}$

Answer: (d) $\frac{3\pi }{4}$

7. Which the following is a dimensionless quantity

(a) Refractive index

(b) Gravitational constant

(c) Velocity

(d) Planck’s constant

8. Calculate the value of the dot product of the two vectors whose magnitudes are 3 units and 4 units and their resultant is 1 unit.

(a) +6 units

(b) 0

(c) -12 units

(d) -1 unit

9. From the given three fundamental constants, select the combination that gives the dimension of length

(i) Newton’s gravitational constant (G)

(ii) Speed of light in a vacuum (c)

(iii) Planck’s constant (h)

(a) $\sqrt{\frac{hc}{G}}$

(b) $\sqrt{\frac{Gc}{h^{\frac{3}{2}}}}$

(c) $\sqrt{\frac{hG}{c^{\frac{5}{2}}}}$

(d) $\sqrt{\frac{hG}{c^{\frac{3}{2}}}}$

Answer: (d) $\sqrt{\frac{hG}{c^{\frac{3}{2}}}}$

10. Following are the readings obtained while measuring the diameter of a wire by using the screw gauge0 mm is the main scale reading

52 divisions are the circular scale reading

What is the diameter of the wire if 1 mm on the main scale is equal to the 100 divisions on the circular scale

(a) 0.016 cm

(b) 0.052 cm

(c) 0.15 cm

(d) 0.05 cm