# Neco Physics Practical Answers – June/July 2019 Runs

**Neco Physics Practical Answers – June/July 2019 Runs**

(1a)

Centre of gravity C G = 50.0cm

(1aviii)

Tabulate:

Under Y(cm): 10; 15; 20; 25; 30;

Under K(cm): 32.7; 35.0; 37.0; 39.0; 41.0;

Under X(cm): 22.7; 20.0; 17.0; 14.0; 11.0;

Under K¹(cm): 29.0; 31.5; 34.3; 36.9; 39.5;

Under X¹(cm): 19.0; 16.5; 14.3; 11.9; 9.5;

(1ax)

Slope = ΔX/ΔX1 = 16 – 8/13.4 – 6.8 = 8/6.6 = 1.21

(1axi)

K = M1 – Sm/S – 1

= 150 – 1.21(100)/1.21 – 1

= 150 – 121/0.21

= 29/0.21

=138

(1axii)

(i)i avoided drought by closing the window

(ii)i avoided error due to parallax when reading the meter rule

(1bi)

Couple is a pair of forces, equal in magnitude, oppositely directed, and displaced by perpendicular distance or moment.

(1bii)

Draw the diagram

Sum of clockwise moment = sum of anticlockwise moment

0.2m = 50 × 0.5

m = 50×0.5/0.2

m = 125g

Mass of beam = 125g

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(NUMBER 3)

(3bi)

Lost volt is the voltage lost due to

the internal resistance of a cell.

It is measured in volts

(3bii)

E= I(R+r)

4=I(2+0.5)

4=2.5I

I=4/2.5

I=1.6A

(3viii)

(Pick two)

(Precaution)

(i)I would ensure that the key is

opened when circuit is not in use

to avoid the cell being used up

(ii)I would ensure that the

electrical wires are tightly

connected

(iii)I would ensure clean

terminals

(3av)

E=3.0v

(3avii)

Tabulate

Under L(cm): 20.0; 30.0; 40.0; 50.0; 60.0; 70.0;

Under I(A): 0.70; 0.60; 0.55; 0.50; 0.45; 0.40;

Under X=E/I(Ohms): 4.2857; 5.0000; 5.4545; 6.0000; 6.6667; 7.5000;

(3aix)

slope = ΔL/ΔX = 66 – 12/7 – 4

= 54/3 = 18cm

Intercept, C

(3ax)

K = 4.9×10^-7

K = 4.9×10^-7 × 18

K = 8.82×10^-6cm/ohm

(3axi)

-I ensured tight connections.

-I avoided error due to parallax on the ammeter.

(3bi)

keep the top or terminals clean.

Do not tighten or remove cables while charging or discharging.

(3bii)

Using ohm’s law

R = V/I = 3.5/0.25 = 14ohm

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Q1.

determine the slope of the graph

and the intercept c

– evaluate k1 = k1 = 4π2/s and k2

=

(Xiii)- state any two of the

following precautions

– Avoided conical oscillations

– Ensured firm suspension of

pendulum

– Ensured reading is repeated

(shown on the table

– Avoided draught

-Corrected/noted for zero error

of metre rule/ stop match/clock

– Avoided parallax error in

reading metre rule/ stop clock

(b) (i) The period of oscillation of

a body is the time taken for the

body to make one complete to

and from movement

(ii) When a body is falling under

its weight (alone), the rate of

increase of its velocity with time

(as a result of the earth’s

gravitational pull) is the

acceleration of free fall due to gravity

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