WAEC Physics Past Questions & Answers - Page 181

901.

A metal rod of length 100cm is heated through 100oC, calculate the change in length of the rod [linear expansivity of the material of the rod is 3 x 10-6K-1]

A.

4mm

B.

3mm

C.

2mm

D.

1mm

Correct answer is B

\(I_2 - I_1 = I_1, \theta\alpha - 1 \times 100 \times 3 \times 10^{-5}\)

= 3 x 10-3m

= 3mm

902.

A platinum resistance thermometer has a resistance 4\(\Omega\) at 0°C and 10\(\Omega\) at 100°C. Assuming the resistance changes uniformly with temperature. Calculate the resistance of the thermometer when the temperature is 45°C.

A.

14.0\(\Omega\)

B.

6.7\(\Omega\)

C.

3.2\(\Omega\)

D.

2.7\(\Omega\)

Correct answer is B

\(\frac{R - 4}{10 - 4} = \frac{45 - 0}{100 - 0}\)

R = \(\frac{670}{100} = 6.7\Omega\)

903.

Which of the following statements correctly defines a simple machine? a device

A.

that can provide electric current

B.

which can only carry people from one place to another

C.

with which work can be done easily

D.

which changes the state of rest or of uniform motion of an object along a straight ine

Correct answer is C

No explanation has been provided for this answer.

904.

A ball f mass 5.0kg hits a smooth vertical wall normally with a speed of 2ms-1. Determine the magnitude of the resulting impulse

A.

2.0kgms-1

B.

10.0kgms-1

C.

5.0kgms-1

D.

2.5kgms-1

Correct answer is B

I = Ft = m(v - u) = 5 x 2

= 10kgms-1

905.

The mass on a loaded spiral spring oscillates vertically between two extreme positions P and R equidistant from the equilibrium position Q. Which of the following statements about the system is not correct

A.

the momentum of the mass is maximum at Q

B.

the elastic potential energy of the spring is maximum at Q

C.

the kinetic energy of the mass is maximum at P

D.

the total energy of the system is always constant

Correct answer is D

No explanation has been provided for this answer.