JAMB Physics Past Questions & Answers - Page 341

1,701.

An object of volume 1 m 3 and mass 2kg is totally immersed in a liquid of density 1 kgm-3 . Calculate its apparent weight.

A.

20N

B.

10N

C.

2N

D.

1N

Correct answer is B

M = DV = 1 x 1 = 1kg

App Wt = (2 - 1)g = 1 x 10

= 10

1,702.

If a load of 1 kg stretches a cord by 1.2cm, what is the force constant of the cord? {g=10ms-2}

A.

866Nm-1

B.

833Nm-1

C.

769Nm-1

D.

667Nm-1

Correct answer is B

K = \(\frac{F}{e}\)

K = \(\frac{1 \times 10}{\frac{0.2}{100}}\)

K = \(\frac{10}{12} \times \frac{1000}{1}\)

1,703.

A block and tackle is used to raise a load of 250N through a vertical distance of 30m. What is the efficiency of the system if the work done against friction is 1500J?

A.

62.5%

B.

73.3%

C.

83.3%

D.

94.3%

Correct answer is C

Y = \(\frac{work output}{work input} \times \frac{100}{1}\)

Y = \(\frac{250 \times 30}{250 \times 30 + 1500} \times \frac{100}{1}\)

1,705.

An object moves in a circular path of radius 0.5m with a speed of 1ms-1 What is its angular velocity?

A.

8 rads-1

B.

4 rads-1

C.

2 rads-1

D.

1 rads-1

Correct answer is C

W = \(\frac{v}{r} = \frac{1}{0.5}\)