JAMB Physics Past Questions & Answers - Page 131

651.

The fig above shows two waveforms X and Y. If the frequency of X is 30Hz what is the frequency of Y

A.

12Hz

B.

19Hz

C.

60Hz

D.

75Hz

Correct answer is D

No explanation has been provided for this answer.

652.

in the image above, an incident ray XY makes an angle of 15\( ^{\circ} \) with a fixed line AY which is normal to surface of a plane mirror if the mirroe is turned as indicated by the arrow through \( 40^{\circ} \) what angle will the reflected ray make with AY

A.

\( 25^{\circ} \)

B.

\( 40^{\circ} \)

C.

\( 15^{\circ} \)

D.

\( 55^{\circ} \)

E.

\( 95^{\circ} \)

Correct answer is E

incident ray = XY

incidence angle i = 15\( ^{\circ} \)

rotation angle θ = 40º

angle that the reflected ray make with AY = i + 2θ  

= 15 + [2 * 40] = 15 + 80 = 95º

654.

the fig above shows three different ways of hanging a heavy picture from a hook. the tension in the string will be?

A.

Greatest in X

B.

Greatest in Y

C.

Greatest in Z

D.

Same in each one

Correct answer is B

Gravity is always directed in a vertical fashion at X (i.e. 90 degrees which is where tension will be minimum). 

 The more horizontally aligned the cable is, the more it will pull horizontally. This increased horizontal pull will increase the tension in the cable.

655.

the fig above shows displacement-time graphs for three different motions. which of the following statements is correct?

A.

graph 2 corresponds to the highest velocity

B.

graph 1 corresponds to zero velocity

C.

graph 3 corresponds to a particle moving in the negative x direction

D.

graph 2 corresponds to a particle moving in the positive x direction

Correct answer is B

At constant velocity, an object must have a constant speed in a constant direction. Constant direction constrains the object to motion in a straight path thus, a constant velocity means motion in a straight line at a constant speed.