JAMB Physics Past Questions & Answers - Page 227

1,131.

A piece of wood is floating on water. The forces acting on the wood are

A.

upthrust and reaction

B.

weight and reaction

C.

weight and upthrust

D.

upthrust and viscousity

E.

weight and viscousity

Correct answer is C

No explanation has been provided for this answer.

1,132.

Ripples on water are similar to light waves in that they both

A.

have the same wavelength

B.

are longitudinal

C.

cannot be reflected

D.

travel at the same speed

E.

can be refracted and diffracted

Correct answer is E

No explanation has been provided for this answer.

1,133.

What is the cost of running five 50W lamps and four 100W lamps for 10 hours if electrical energy costs 2 kobo per kWh?

A.

N0.65

B.

N0.13

C.

N3.90

D.

N39.00

E.

N234.00

Correct answer is B

PT = (5 x 50) + (100 x 4)

= 650watts

Energy(kWhr) = 650 x 10-3 x 10

= 6.5 kWhr

1kWhr cost 2 kobo ; 6.5 kWhr will cost \(\frac{2 \times 6.5}{1}\)

= 13 kobo

1,134.

Heat is supplied uniformly at the rate of 100W to 1.0 x 10-2kg of a liquid for 20 seconds. If the temperature of the liquid rises by 5oC, then the specific heat capacity of the liquid is

A.

2.0 x 102Jkg-1k-1

B.

2.0 x 102Jkg-1

C.

4.0 x 104Jkg-1k-1

D.

4.0 x 104kg-1

E.

8.4 x 103Jkg-1k-1

Correct answer is C

Heat energy = Electrical energy

mc\(\theta\) = power x time

5 x 1 x 10-2 x C = 100 x 20

C = 4.0 x 104Jkg-1k-1

1,135.

A particle moves in a circular orbit of radius 0.02m. If the speed of the particle is 0.88ms-1, calculate its frequency in cycles per second

A.

2.0Hz

B.

7.0Hz

C.

8.8Hz

D.

14.0Hz

E.

17.6Hz

Correct answer is B

W = \(\frac{v}{r}\)

= \(\frac{0.88}{0.02}\) = 44 rad/s

2\(\pi\)F = W = 44

F = \(\frac{44}{2 \times 3.142}\)

= 7Hz