Post Utme Physics Past Questions and Answers

Question 26:

How much work is done against gravity in sliding a $500\mathrm{g}$ object through $2\mathrm{m}$ up a smooth plane that is inclined at ${30}^{\circ }$ to the horizontal? $(g=9.8\mathrm{ms}-2)$

A. $9.8\mathrm{J}$
B. $19.8\mathrm{J}$
C. $16.2\mathrm{J}$
D. $4.9\mathrm{J}$

Question 27:

If a small body of mass $m$ is moving with angular velocity $w$ in a circle of radius $r$, what is its kinetic energy?

A. Mwr
B. ${\mathrm{mw}}^2\mathrm{r}/2$
C. $\mathrm{m}\omega {\mathrm{r}}^2/2$
D. $\mathrm{m}{}^2{\mathrm{r}}^2/2$

Question 28:

In free fall, two balls of masses $20\mathrm{kg}$ and $10\mathrm{kg}$ were dropped from a height. If the ball with the smaller mass reached the ground after $4\mathrm{s}$, what is the difference between the time the two balls reach the ground?

A. $8\mathrm{s}$
B. $2\mathrm{s}$
C. $0\mathrm{s}$
D. $4\mathrm{s}$

Question 29:

In what distance can a $1,500\mathrm{kg}$ automobile be stopped if the brake is applied when the speed is $20\mathrm{m}/\mathrm{s}$ and the coefficient of sliding friction is $0.7$ between the tyres and the ground?

A. $98.10\mathrm{m}$
B. $71.67\mathrm{m}$
C. $29.15\mathrm{m}$
D. $20.10\mathrm{m}$

Question 30:

The highest point of a simple pendulum bob is $5\mathrm{cm}$ vertically above the lowest point as it swings to and fro between the two extreme ends. At what velocity does it swing past the lowest point (equilibrium point) where the string is vertical? (take $g=10\mathrm{m}/\mathrm{s}2$ )

A. $1\mathrm{m}/\mathrm{s}$
B. $2\mathrm{m}/\mathrm{s}$
C. $5\mathrm{m}/\mathrm{s}$
D. $10\mathrm{m}/\mathrm{s}$