2017 Physics WAEC (WASSCE) Essay Past Questions (Paper 2)

Question 1

A particle is dropped from a vertical height h and falls freely for a time t. With the aid of a sketch, explain how h varies with t².

Answer

Recall: h = ut + ½ gt² ——— (1)

Now, for an object which drops from rest, i.e, u = 0

h = ½ gt² ———- (2)

or

h = 0 + ½ gt² ——– (3)

Compare Equate (3) to y = mx + c

h = 1/2 gt² + 0

y = mx + c

On the y-axis, we have h; and on the x – axis, we have t²; and m (slope) = ½ g

Question 7

A particle is projected horizontally at 15 ms^-1 from a height of 20 m. Calculate the horizontal distance covered by the particle just before hitting the ground. [g= 10 ms^-2 ]

(Leaving the answer in whole numbers)

Solution

U_x = 15 ms^-1 (horizontal velocity)
H = 20 m
R = Unknown
Diagrammatically, we have

Recall:

H = U_y t + ½ gt²

U_y  = 0

H = ½ gt² —————- *

20 = ½ × 10 × t²

40 = 10t²

t² = 4

t = 2 s

Recall:

R = U × T

R = (15)(2) = 30 m

Question 3

List three phenomena which can be explained by the molecular theory of matter.

Answer

The following phenomena can be explained by the molecular theory of matter:

i. Brownian movement
ii. Diffusion
iii. Effusion
iv. Osmosis
v. Viscosity
vi. Evaporation