WAEC Physics Past Questions & Answers - Page 171

851.

A force acting on a body causes a change in the momentum of the body from 12kg ms-1 to 16kg ms-1 in 0.2s. calculate the magnitude of the force

A.

140.0N

B.

20.0N

C.

4.0N

D.

0.8N

Correct answer is B

F = \(\frac{mv - mu}{t} = \frac{16 - 12}{0.2} = 20N\)

852.
853.

A body is said to be moving with uniform acceleration if it experiences equal

A.

increase in velocity at equal time intervals

B.

decreases in velocity at equal time intervals

C.

increases in speed at equal time intervals

D.

decreases in speed at equal time intervals

Correct answer is A

No explanation has been provided for this answer.

854.

The speed of an object in rectilinear motion can be determine from the

A.

area under a velocity-time graph

B.

area under a distance-time graph

C.

slope of a distance-time graph

D.

slope of a velocity-time graph

Correct answer is C

No explanation has been provided for this answer.

855.

A machine of velocity ratio 5 is used in lifting a load with an effort of 500N. If the machine is 80% efficient. Determine the magnitude of load

A.

2500N

B.

2000N

C.

900N

D.

625N

Correct answer is B

M.A = \(\frac{Eff \times V.r}{100} = \frac{80 \times 5}{100} = 4\)

Load = effort x M.A

= 4 x 500 = 2000N