2015 - JAMB Physics Past Questions and Answers - page 4

Heat capacity (o) = mass (kg) specific heat of a substance (C₂)

i.e Q = MC

where Q = 40 J/L, m = ?(380 J/Kgk)

40 = m × 380

m = 0.11kg (Approx)

Using the equation

S = ut + ½ gt²

H = s = 20m, t = ?

G =10m/s², u = 0m/s

20 = 0 × t × ½ × 10 t

20 = 5t

i.e 5t² = 20

t = 20/5 = 4

t = 4 (squaring both sides)

√ t² = √4

= 2sec

∴ t = 2sec

Velocity Ratio (V.R) = distance moved by the effort (x)÷ distance moved by the load (y)

i.e. V.R = x/y

v. R = 5, x/y = ?

i.e x/y = 5/1; , where x = 5, y = 1

x : y = 5 : 1

Mechanical advantage (M.A) of a machine is the ratio of its load to effort

Mathematically

Mechanical advantage (M.A) = Load (L) ÷ Effort (E)

In symbol M.A = L/E

Note:Mechanical (advantages has no S.I unit)

If M.A = 4 then,

L/E = 4/1

The ratio of load to effort = 4 : 1 respectively

A gas thermometers are more besting use to achieve an accurate temperature than others, such as liquid in glass thermometers such as mercury, clinical and alcohol thermometer

(Neglect of Air resistance)

Note: Both objects reach the ground at the same time

M= 3kg, r = 0.7m, v = 2m/s

v = wr

w = angular velocity

r = radius in an tangential circular

v = speed of an object

W = V/δ = 2/ 0.7 = 2.85

W = 2.853rads–1 (total interest whole number)

W = &approx.; 3rads–1Angular velocity (w) = 3rads^–1

Microscope is used for nearby object

Electron: A sub–atomic particle haring a negative charge and orbiting the nucleus (note: the symbol 0–1e represent the particle of an electrons.)

Wavelength (Λ) = 10 ^-13m

Speed of X-ray = speed of light C = 3×10³m/s

Frequently (f) = ?

Using V = fΛ (or (– f π for electromagnetic wave)

f = c/Λ = 3 × 10⁸ ÷ 10^-13 = 3 × 10³ × 10³

= 3 × 10¹³ × 10¹³

= 3 × 10²¹HZ