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.

491.

When water is boiling, it

A.

gets hotter

B.

increase is mass

C.

decreases in mass

D.

changes to steam

Correct answer is D

Boiling indicates changes from Liquid to gas.

492.

The lead-acid accumulator consists of

A.

lead as the positive electrode

B.

lead acid as the negative electrode

C.

hydrochloric acid as the electrolyte

D.

tetraoxosulphate (vi) acid as the electrolyte

Correct answer is D

- the positive pole is lead peroxide (PbO\(_2\))
- the negative pole is head
- the electrolyte is H\(_2\)SO\(_4\)

493.

A metal rod has a length of 100cm at 200°C. At what temperature will its length be 99.4cm. If the linear expansivity of the material of the rod is 2 × 10\(^{-5}\)C\(^{-1}\)

A.

\(300^0C\)

B.

\(200^0C\)

C.

\(100^0C\)

D.

\(-100^0C\)

Correct answer is D

L\(_1\) = 100cm, T\(_1\) = 200°C
L\(_2\) = 99.4cm, T\(_2\) = ?
α 2 × 10\(^{-5}\) C\(^{-1}\)

494.

The momentum of a car moving at a constant speed in a circular track

A.

can be both positive and negative

B.

can be zero depending on its position in the track

C.

can be zero depending on its inertia in the track

D.

a centrifugal

Correct answer is C

Movement of an object in a circle with an acceleration towards its center is provided by change in velocity & centripetal force a α V α Fc

495.

A force of 6N acts horizontally on a stationary mass of 2kg for 4s. The kinetic energy gained by the mass is _________

A.

366j

B.

240j

C.

144j

D.

90j

Correct answer is C

F = 6N, m = 2kg, t = 4s, u = 0 (stationary or at rest)

 

K.E = 1
2
mv\(^2\)

 

F = mv
t

from rest

K.E = 1
2
m( Ft
m
)\(^2\) = 1
2
× 2 x (\(\frac{6 \times 4}{2})^2 = 12^2 = 144J\)