2021 - JAMB Physics Past Questions and Answers - page 2

Given: \(\frac{m_{1}}{m_{2}} = \frac{3}{1}\) \(\Rightarrow\) m\(_{1}\) = 3m\(_{2}\)

\(\frac{a_{1}}{a_{2}} = \frac{2}{9}\) = a\(_{1}\) = \(\frac{2a_{2}}{9}\)

\(\frac{F_{1}}{F_{2}}\) = ?

F = ma

\(\Rightarrow\)  \(\frac{F_{1}}{F_{2}} = \frac{m_{1}a_{1}}{m_{2}a_{2}}\)

= \(\frac{(3 \not m_{2})(2 \not a_{2})}{\not m_{2} a_{2} \not a_{3}}\)

\(\frac{F_{1}}{F_{2}} = \frac{2}{3}\) \(\Rightarrow\) 2:3

Given:

m = 10\(^{-2}\)
w = 100rads\(^{-1}\)
F = mw\(^{2}\)r
r = 0.2m

= 10\(^{-2}\) x (100)\(^{2}\) x 0.2

= 20N

V = \(\frac{2d}{t}\) 
v = 340ms\(^{-1}\)
t = 0.5s
d= ?

d = \(\frac{2d}{2} = \frac{340 \times 0.5}{2}\) = 85m

Vector quantities are physical quantities characterized by the presence of both magnitude and direction. Examples of vector quantities are displacement, force, torque, momentum, acceleration, velocity, etc.

Scalar is a physical quantity that is completely described by its magnitude. Examples of scalars are speed, density, volume, energy, mass, time, etc.

H = mc\(\bigtriangleup\theta\) + mL

m = 50g, c = 4.23J/gk,L = 2260, \(\bigtriangleup\theta\) = 80ºC

H = 50 [4.23 x 80 + 2260]

= 129920 \(\approx\) 130,000J

AT resonance; X\(_{L}\) = X\(_{c}\)

V\(_{L}\) = V\(_{c}\) = 40V

Given:

f = 1.6 x10\(^{16}\)H\(_{3}\)

h = 6.63 x 10\(^{-39}\)Js

e = 1.6 x 10\(^{-19}\)C, V = ?

V = \(\frac{w}{e} = \frac{hf}{e}\) 

= \(\frac{1.6 \times 10^{16} \times 6.63 \times 10^{34}}{1.6 \times 10^{-19}}\)

= 66.3V

Given fraction of the atoms left = \(\frac{1}{64}\)

= \(\frac{1}{64} = \frac{1}{(2)^{6}}\)

\(\therefore\) = \(\frac{120 \text {years}}{6}\) = 20 years

\(\Rightarrow\) T\(\frac{1}{2}\)

= 20 years