2017 - WAEC Physics Past Questions and Answers - page 1

Impulse = Force \(\times\) time

Force has the dimension \(\frac{ML}{T^{2}}\), hence 

Impulse= \(\frac{ML}{T^{2}} \times T = \frac{ML}{T}\)

Given that \(u = 0ms^{-1}, a = 2ms^{-2}, s = 9m\)

We can use the equation, \(v^{2}=u^{2} +2as\) so that we have,

\(v^{2} = 0^{2} + 2\times 2\times 9\)

\(v^{2} = 36; v= 6.0ms^{-1}\)

Note; u = Initial velocity

v = final velocity

a = acceleration

s = distance covered

All other properties of the different states of matter holds except that the molecules of solids don't move freely due to the fact that the particles in the solids are closely packed so it inhibits free motion.

The body while coming down is acted upon by acceleration due to gravity, hence, the vertical force is constant. Also, at maximum height, the vertical velocity is 0 and then increases as the body comes downward.

Upthrust = weight of liquid displaced

= mass of liquid displaced \(\times\) acceleration due to gravity

= \(\frac{200}{1000} \times 10\)

= 2N

It is a type of beam balance with great precision, and it can pick up the slightest mass placed on it.

Convert velocity from \(kmh^{-1}\) to \(ms^{-1}\), by multiplying \(\frac{1000}{3600}\), 

\(72 \times \frac{1000}{3600}\) = \(20ms^{-1}\)

Therefore, distance covered in 0.4s =  \(20 \times 0.4 = 8m\)