## Physics 2018 | Study Mode

Question 1
A
Hz
B
cd
C
dB
D
Explanation.

Every form of energy is measured in joules (J).

Question 2
A
$$\frac{stress}{strain}$$
B
$$\frac{strain}{stress}$$
C
$$stress \times strain$$
D
$$\sqrt{\frac{stress}{strain}}$$
Explanation.

Elastic modulus is the ratio of pressure (stress) applied to a body to the resistance (strain) produced by the body.

= $$\frac{stress}{strain}$$

Question 3
A
PQ
B
QR
C
RS
D
QS
Explanation.

The height of the mercury column in a simple barometer is calculated as the atmospheric pressure.

Question 4
A
momentum
B
Inertia
C
impulse
D
Energy
Explanation.

Inertia is the resistance of the object to any change in its motion, including a change in direction. An object will stay still or keep moving at the same speed and in a straight line, unless it is acted upon by an external unbalanced force.

Question 5
A
thickest at the top
B
thickest at the middle
C
thickest at the bottom
D
of the same thickness throughout
Explanation.

The pressure of the water is much greater deeper down and the dam needs to be thick at the bottom so that it is strong enough to withstand this larger pressure.

Question 6
A
Fv
B
zero
C
Fmr
D
$$\frac{Fr}{m}$$
Explanation.

The work done by centripetal force in the case of a uniform circular motion is 0 joules.

Question 7
A
I and III only
B
I and II only
C
II and III only
D
I, II and III
Explanation.

In SHM, the body must have acceleration in a direction opposite to the displacement and the acceleration must be directly proportional to displacement. Also, the acceleration must be directed towards its mean position. This is not the case with a football on the pitch.

Question 8
A
6kg
B
9kg
C
10kg
D
15kg
Explanation.

Total force exerted on the block = (10 - 1)N =9N

Force = mass x acceleration

9 = m x 1.5

m = 9/1.5 = 6kg

Question 9
A
I and II
B
II, III and IV
C
I, II, III and IV
D
I, III and IV
Explanation.

The quantities Efficiency, Dielectric constant and Refractive index are dimensionless.

Question 10
A
The vertical distance covered
B
Acceleration due to gravity
C
The horizontal distance covered
D
The acceleration of the body
Explanation.

$$R_{max} = \frac{u^{2}}{g}$$

Hence, $$g = \frac{u^{2}}{R_{max}}$$

Question Map