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JAMB Physics Past Questions & Answers - Page 328

1,636.

A ball is moving at 18ms^-1 in a direction inclined at 60^o to the horizontal. The horizontal component to its velocity is

9√3ms^-1 ·

6√3ms^-1 ·

8√3ms^-1 ·

9ms^-1 ·

View answer & explanation

Correct answer is D

No explanation has been provided for this answer.

1,637.

The physical quantity that has the same dimensions as impulse is

energy

momentum

surface tension

pressure

View answer & explanation

Correct answer is B

Impulse = F x t = m(v-u)

1,638.

The velocity of a sound wave at 27^oC is 360ms^-1. Its velocity at 127^oC is

120√3 ms^-1

240 ms^-1

240√3 ms^-1

720√3 ms^-1

View answer & explanation

Correct answer is C

Velocity $\alpha \sqrt{temperature}$

$\frac{V_1}{V_2} = \sqrt{\frac{T_1}{T_2}}$

therefore, $\frac{360}{V_2} = \sqrt{\frac{27 + 273}{127 + 273}}$

$V_2 = 240\sqrt{3}$ m/s

1,639.

A bullet fired at a wooden block of thickness 0.15m manages to penetrate the block. If the mass of the bullet is 0.025kg and the average resisting force of the wood is 7.5 x 10³N, calculate the speed of the bullet just before it hits the wooden block.

450ms^-1

400ms^-1

300ms^-1

250ms^-1

View answer & explanation

Correct answer is C

F = ma

Therefore, a = $\frac{F}{m}$

a = $\frac{7.5 \times 10^{3}}{0.025}$

a = 3 x 10⁵m/s²

using V² = U² + 2ax;

V² = 0² + (2 x 3 x 10⁵ x 0.15)

Therefore V = 300 m/s