JAMB Physics Past Questions & Answers - Page 310

1,546.

An object is projected with a velocity of 80ms-1 at an angle of 30o to the horizontal.The maximum height reached is

A.

20m

B.

80m

C.

160m

D.

320m

Correct answer is B

max. height = \(\frac{U^2\sin^2\theta}{2g}\)

= \(\frac{80 \times 80 \times \sin^2(30)}{2 \times 10}\)

= 80m

1,547.

A boat travels due east at a speed 40ms-1s across a river flow due south at 30ms-1s. What is the resultant speed of the boat?

A.

1.3ms-1

B.

10.0ms-1

C.

50.0ms-1

D.

70.0ms-1

Correct answer is C

No explanation has been provided for this answer.

1,548.

If it takes 5.0 hrs to drain a container of 540.0cm3 of water, what is the flow rate of water from the container in kg-1? [Density of water = 1000kgm-3]

A.

32.5kg-1 s

B.

31.5kg-1

C.

30.8kg-1 s

D.

30.0kg-1 s

Correct answer is D

Flow = rate = \(\frac{mass}{time}\)

= \(\frac{1000 \times 540}{5 \times 3600}\)

= 30.0kg-1 s

1,550.

The primary winding of a transformer has 400 turns and its secondary has 100 turns. If a source of e.m.f. of 12V is applied to the primary, the secondary e.m.f. will be

A.

3V

B.

6V

C.

24V

D.

48V

Correct answer is A

\(\frac{V_s}{V_p}\) = \(\frac{N_s}{N_p}\) = \(\frac{I_p}{I_s}\)

\(\frac{100}{400}\) = \(\frac{V_S}{12}\)

V = 3V