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Physics questions and answers

Physics Questions and Answers

If you want to learn more about the nature and properties of matter and energy or you're simply preparing for a Physics exam, these Physics past questions and answers are ideal for you.

1,341.

If the total force acting on a particle is zero, the linear momentum will

A.

Increase

B.

Decrease

C.

Be Constant

D.

Increase then decrease

Correct answer is C

No explanation has been provided for this answer.

1,342.

In a fission process, the decrease in mass is 0.01%. How much energy could be obtained from the fission of 0.1g of the material

A.

9.0×109J

B.

9.0×1010J

C.

6.3×1011J

D.

9.0×1011J

Correct answer is A

In general, the energy released during nuclear fission is given by the Einstein's mass-energy equation, given by

E=ΔMC2

Where Δm is the mass defect, and C is the speed of light.
Therefore
Δm=0.01×1.0g=1.0×104=1.0×107kgEnergy Released =ΔMC2=1.0×107×(3.0×108)2=1.0×102×9.0×1016=9.0×109J

1,343.

If the uncertainty in the measurement of the position of a particle is 5.0 x 10-10m, the uncertainty in the momentum of the particle is

A.

1.32 x 10-44Ns

B.

3.30 x 10-44Ns

C.

1.32 x 10-24Ns

D.

3.30 x 10-24Ns

Correct answer is C

From the uncertainty principle the product of the position and momentum of a sub-atomic particle is equal or greater than planck's constant.

i.e Δx.Δph.Thus5×1010×Δp=6.6×1034Δp=6.6×10345×1010=1.32×1024NsTherefore Uncertainty in the momentum =1.32×1024Ns

1,344.

Given that young's modulus for aluminium is 7.0 x 1010Nm-2 and density is 2.7 x 103kgm-3 find the speed of the sound produced if a solid bar is struck at one end with a hammer

A.

5.1 x 103ms-1

B.

4.2 x 103ms-1

C.

3.6 x 103ms-1

D.

2.8 x 103ms-1

Correct answer is A

The speed of sound in a material is given as:

V=EP,WhereE=Young's modulusP=Density Therefore V=7.0×10102.7×103=5091.75=5.1×103MS1

1,345.

A force of 100N was used to kick a football of mass 0.8kg. Find the velocity with which the ball moves if it takes 0.8s to be kicked

A.

32ms1

B.

50ms1

C.

64ms1

D.

100ms1

Correct answer is D

From Newton's second law:

F = \frac{mV - mµ}{t}

Let the final velocity = V; and since the football is initially at rest, its initial vel µ = 0, M = 0.8kg

t = 0.8s \\ \implies 100 = \frac{0.8V - 0.8 \times 0}{0.8} \\ \text{Therefore } V = \frac{100 \times 0.8}{0.8} = 100ms^{-1}