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.

666.

A force of 5N acts at a point Y on a rod XYZ as shown in this diagram. If XYZ is 2m, what is the moment of the force about point X?

A.

0Nm

B.

3Nm

C.

7Nm

D.

10Nm

Correct answer is A

using the formular :

Moment = Force × Distance
5 X 0 = 0Nm           

667.

The energy needed to move a unit positive charge around a complete electric circuit is called the

A.

electromotive force

B.

electric potential difference

C.

electric energy

D.

kinetic energy

Correct answer is B

Electric potential difference: work needed per unit of charge to move a test charge between the two points.
Electric energy: energy derived from electric potential energy.
Kinetic energy: moving energy

668.

An object is placed 20cm from a concave mirror of focal length 10cm. The linear magnification of the image produced is?

A.

0

B.

\(\frac{1}{2}\)

C.

1

D.

2

Correct answer is C

\(\frac{I}{V}\) = \(\frac{1}{f}\) – \(\frac{1}{u}\)

\(\frac{I}{V}\) = \(\frac{1}{10}\) – \(\frac{1}{20}\)

  = \(\frac{1}{20}\) V

  V = 20cm.

  M = \(\frac{V}{U}\)

  = \(\frac{20}{20}\)

  = 1

669.

The tendency of a body to remain at rest when a force is applied to it is called.

A.

Impulse

B.

Momentum

C.

Inertia

D.

Friction

Correct answer is C

Inertia, property of a body by virtue of which it opposes any agency that attempts to put it in motion or, if it is moving, to change the magnitude or direction of its velocity. Inertia is a passive property and does not enable a body to do anything except oppose such active agents as forces and torques. A moving body keeps moving not because of its inertia but only because of the absence of a force to slow it down, change its course, or speed it up.
There are two numerical measures of the inertia of a body: its mass, which governs its resistance to the action of a force, and its moment of inertia about a specified axis, which measures its resistance to the action of a torque about the same axis.

670.

A 20kg mass is to be pulled up a slope inclined at 30° to the horizontal. If efficiency of the plane is 75%. The force required to pull the load up the plane is J [g=10ms\(^{− 2}\)]

A.

87N

B.

73.5N

C.

133.3N

D.

533.2N

Correct answer is C

V. R = \(\frac{1}{Sinθ}\)

  m = 20kg

  V.R = \(\frac{1}{Sin 30}\)

  = 2

  Efficiency = 75%

  Load = mg

  = 20 x 10 = 200N

  Efficiency = \(\frac{M.A}{V.R} \times 100\)

  75/100 = \(\frac{M.A}{2}\)

  M .A = \(\frac{75 \times 2}{100}\)

  M. A = 1.5

  Since M. A. = \(\frac{\text{Load}}{\text{Force}}\)

  Force = \(\frac{200}{1.5}\)

  = 133.3N