JAMB Physics Past Questions & Answers - Page 208

1,036.

The driver in a motor car, of which the total mass is 800kg and which is traveling at 20ms-1, suddenly observes a stationary dog in his path 50m ahead. If the car brakes can exert a force of 2000N, what will most likely happen?

A.

the car will be able to stop immediately the driver notices the dog

B.

the car will stop 30m after hitting the dog

C.

the car will stop 20m in front of the dog

D.

the driver will quickly reverse the car

E.

the car will stop 5m beyond the dog

Correct answer is B

F=ma
2000=800 x a
a = \(\frac{2000}{800}\) → 2.5

V\(^2\)=u\(^2\)+2as
400=2 × 2.5 × S
S =400 ÷ 5 → 80
: 80 - 50 = 30
The car will stop 30m after hitting the dog

1,037.

All of the following frequencies are overtones of 320 Hz EXCEPT

A.

960Hz

B.

640Hz

C.

520Hz

D.

1280Hz

E.

1600Hz

Correct answer is C

Overtones are frequency which are multiples of fundamental frequency

Fundamental frequency - f1 = 320Hz

Overtones 320 x 2 = 640Hz

320 x 3 = 960HZ

320 x 4 = 1280Hz

320 X 5 = 1600hZ

1,039.

The resistance of a 240V, 60 watt electric filament bulb is

A.

0.25\(\Omega\)

B.

480\(\Omega\)

C.

60\(\Omega\)

D.

240\(\Omega\)

E.

960\(\Omega\)

Correct answer is E

power = IV

power = \(\frac{V^2}{R}\) = 60

= \(\frac{240^2}{R}\)

= 960\(\Omega\)

1,040.

When a ray of light passes from water to glass, it is

A.

bent away from the normal

B.

bent towards the normal

C.

totally internally reflected

D.

absorbed by the glass

E.

broken into a pure spectrum

Correct answer is B

No explanation has been provided for this answer.