Neco 2017 Physics Theory And Obj Answers – May/June Expo ~ BLACKLOADED

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PHYSICS OBJ:

1-10 CEABCBAABB

11-20: DCCBCBCCAE

21-30: BECDDBEDDE

31-40: DBAEADBABA

41-50: CBDCBBBDCB

51-60: CEDDCBAEAA

PART I - ANSWER 6

1ai)

i)propellant

ii)nozzle

1aii)

i)used for communication

ii)used for access geographically dispersed terrains and uneven topography that characterise the nations landscappe

1b)

Given: Object distance for eyepiece, U=3.0cm

Final image distance, V=?

Focal length of eyepiece, F=5.0cm

using the mirror/lens formular

1/f=1/u+1/v

1/5=1/3+1/v

multiplying through with 15v(1.cm)

3v=5v+15

3v-5v=15

-2v=-15/2

V=7.5cm

the final image is virtual and 7.5cm from the eyepiece on the same side of the eyepiece as the object

Given Radius, r=25m

linear velocity, v=20m|s

centripetal acceleration,a=?

Using:

a=V^2/r2

a=20^2/25

a=16m|s^2

6a)

A wave front is the locus of points characterized by propagation of position of the same phase: a propagation of a line in 1D, a curve in 2D or a surface for a wave in 3D. In other words a line or surface in the path of an advancing wave on which all the particles are vibrating in phase is called a wave front.

6b)

i)plane wave front

ii)spherical wave front

Pupil- Regulates the amount of light entering the eye

Shutter-admits or shuts off light from the film of the camera

Screen-used to focus light from a near object in front of the pinhold camere

9a)

i)over charging (for secondary cell)

ii)self discharge (for primary cell)

9b)

self discharge- a primary cell lose a considerable percentage of their charge when stored at room temperature, this is due to non-current-producing "side" chemical reactions that occur within the cell even when no load is applied

10)

i)fusion is more easily achieved with lightest elements such as hydrogen

ii)the raw materials required for fussion are more cheaply and readily available

iii)fusion process produce less dangerous by product

PART II - ANSWER 4

12ai)

Newton's second law of motion states that the rate of change of momentum is proportional to the impressed fotvr and takes place in the direction of the force

12aii)

i)a swinging pendulum

ii)The motion of the balance wheel of a watch

12bi)

Resultant force is that single force which acting alone will have the same effect in magnitude and direction as two or more forces acting together

12bii)

Equilbrum force is that single force which will balance all the other forces taken together. It is equal in magnitude buy opposite in direction to the resultant force

12ci)

Resultant,Force,F=sqr4^2+3^2

F=sqr16+9

Fsqr25=5N

12cii)

using F=m(v-u)/t

5=5.5(v-2)/(5*60)

5*60*5=5.5(v-2)

=5.5(v-2)=1500

V-2=272.7

V=272.7+2

V=274.7m|s

final velocity of body = 274.7m|s

PART II - ANSWER 4

12ai)

Newton's second law of motion states that the rate of change of momentum is proportional to the impressed fotvr and takes place in the direction of the force

12aii)

i)a swinging pendulum

ii)The motion of the balance wheel of a watch

12bi)

Resultant force is that single force which acting alone will have the same effect in magnitude and direction as two or more forces acting together

12bii)

Equilbrum force is that single force which will balance all the other forces taken together. It is equal in magnitude buy opposite in direction to the resultant force

12ci)

Resultant,Force,F=sqr4^2+3^2

F=sqr16+9

Fsqr25=5N

12cii)

using F=m(v-u)/t

5=5.5(v-2)/(5*60)

5*60*5=5.5(v-2)

=5.5(v-2)=1500

V-2=272.7

V=272.7+2

V=274.7m|s

final velocity of body = 274.7m|s

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13ai)

i)Solar energy is for providing a cheap and clean source of hot water supply.

ii)Solar energy provides electricity supply

13aii)

Renewable energy are those that can be replaced as they are used up. They can be continually replenished as they are exploited and utilized while Non-Renewable energy are those that cannot be replenished as they are used up

13b)

The principle of conservation of linear momentum us also utilized in the propulsion of jet aircraft. Gases are burnt within the combustion chambers of the engine. As jets of hot gases are expelled downwards through the tail nozzle at very high speeds from the aircraft, an equal and opposite momentum is given to the rocket or aircraft which then moves

13c)

Given: mass, m=0.2kg

heat lost,it=4200J

intial temperature cost r= 100'C

final temperature cost=?

S. It . c of water, C10=4200J/kg/k

using:

heat lost= M10, C10 (cost-tf)

400=0.2*4200*(100-costf)

=4200/0.2*4200

100-costF=5

100-5=costf

=cost=100-5

costf=95'C

final temperature=95'C

=======================

14ai)

A transverse wave is one which travels perpendicularly to the direction of the vibration producing the wave.

14aii)

i)Light Wave do not need a material medium for preparation, but sound wave does

ii)Light wave cannot be plane polarised but sound wave can

14b)

Given Y= 4sin (100x22/7xt/2 + 0.5x)

Comparing with

Y = A sin (2xPIxft + 2pi/pi x) Note : {the PI is the 22/7}

14bi)

2 x 3.142/0.5 = 12.56cm

Hence Wave length is 12.56

14bii)

Also 1000PI/wave length = 2PI F

= 1000PI/12.56 = 500/12.56

= 39.8Hz

14biii)

Speed (v) = F x Wave length

= V = F x Wave Length

V = 500/12.56 x 12.56

= 500cm/s

Conversation to M = 500/100

= 5m/s

15a)

Coulomb's Law state that the magnitude of the electrostatic force between two point charges is directly proportional to the product of the magnitudes of the charges and inversely proportional to the square of the distance between them.

15bi)

diagram

I<-V

15bii)

let equivalent resistance be R

1/R=1/R1+1/R2+1/R3

1/R=R2,R3+R1,R3+R1,R2/R1,R2,R3

R=R1,R2,R3/R1,R2,+R2,R3+R1,R3

15C)

Given; R=20n,C=4HF,F=50H2,TI=3.14

z=sqr R^2+(1/2TiFc)

z=sqr200^2+(1/2*314*50*4*10^-6)