2017 - WAEC Physics Past Questions and Answers - page 2

The formula is \(\frac{v^{2}sin2\theta}{g}\) 

And the sine graph is highest at 1 with its inverse as 90°. Hence, \(2\theta\) = 90°

\(\theta\) = 45°

Relative motion is the calculation of the motion of an object with regard to some other moving object. Hence, relative motion is not a type of motion.

The quantity of heat needed to melt ice = mL (where m is the mass of ice and L is the specific latent heat of fusion of ice)

Q = \(50 \times 336 = 16800J\) but this is 70% of the total heat supplied so that we have,

70% total heat = 16800J

\(\frac{70}{100} heat = 16800J\)

Total heat supplied = \(\frac{16800\times100}{70} = 24000J\)

Velocity ratio = \(\frac{Effort distance}{Load distance}\)

On an inclined plane, it is the inverse of \(sin\theta\) = \(\frac{1}{sin\theta}\)

When a bubble is deep under water, it has both atmospheric pressure and water pressure (giving it depth), acting on it but as it rises, the water pressure decreases. At this point, the basic pressre acting on the bubble is the atmospheric pressure. Recall that pressure is inversely proportional to volume (Boyles' law), hence, the less the pressure, the more the volume.

The solar cell converts light from the sun to electricity.

Latent heat is thermal energy released or absorbed, by a body or a thermodynamic system, during a constant-temperature process.

This is as a result of the Hydrogen bonding in water. Due to the high Kinetic Energy of water, the hydrogen bonds can't hold for too long but from 4°C, there's an increase in the hydrogen bonds hence strenghtening it.  From the point of production of more hydrogen bonds, the bonding is no longer easily broken. Generally, these and a few factors based on these cause the density of water to be maximum at 4°C.