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JAMB UTME - Physics - 2014

Ibeere 1 Ìròyìn

PHCN measures its electrical energy in

W

KWh

Wh

J

Awọn alaye Idahun

The PHCN, or Power Holding Company of Nigeria, measures its electrical energy in kilowatt-hours (KWh). This is a unit of energy that is commonly used to measure the amount of electricity that is consumed or generated over a period of time. A kilowatt-hour is equivalent to the amount of energy consumed or generated by a one kilowatt power source in one hour. So, by measuring the electrical energy in kilowatt-hours, PHCN can keep track of how much electricity is being used by its customers and bill them accordingly.

Ka ìwé ẹ̀kọ́ nípa Electric Cells (JAMB)

Electric Cells

Ibeere 2 Ìròyìn

A car accelerates uniformly from rest at 3ms-2. its velocity after traveling a distance of 24m is

12ms-1

144ms-1

72ms-1

36ms-1

Awọn alaye Idahun

V2 = U2 x 2ax
V2 = 0 x 2(3)(24)
V2 = 144
V =

\sqrt{144}

V = 12ms-1

Ka ìwé ẹ̀kọ́ nípa Motion (JAMB)

Ibeere 4 Ìròyìn

An object is placed 10m from a pinhole camera of length 25cm. Calculate the linear magnification.

2.5x102

2.5x10-2

2.5x10-1

2.5x101

Awọn alaye Idahun

Linear Magnification = \frac{Length of Camera}{Distance of the Object}

$Linear Magnification = \frac{25}{1000}$

$Linear Magnification = 2.5 \times 10^{- 2}$

Ka ìwé ẹ̀kọ́ nípa Electrostatics (JAMB)

Electrostatics

Ibeere 12 Ìròyìn

A wheel and an axle is used to raise a load whose weight is 800N when an effort of 250N is applied. If the radii of the wheel and axle are 800mm and 200mm respectively, the efficiency of the machine is

90%

80%

85%

87%

Awọn alaye Idahun

VR = 800/200 = 4

E f f i c i e n c y = \frac{M A}{V R} \times \frac{100}{1}

$E f f i c i e n c y = \frac{L}{E} \times \frac{1}{V R} \times \frac{100}{1}$

$E f f i c i e n c y = \frac{800}{250} \times \frac{1}{4} \times \frac{100}{1}$

= 78.74%
= 80%

Ka ìwé ẹ̀kọ́ nípa Simple Machines (JAMB)

Simple Machines

Ibeere 15 Ìròyìn

A machine whose efficiency is 75% is used to lift a load of 1000N. Calculate the effort put in to the machine if it has a Velocity ratio of 4.

343.32N

233.33N

333.33N

334.33N

Awọn alaye Idahun

\frac{M A}{V R} \times \frac{100}{1} = e f f i c i e n c y

$\frac{L}{E} \frac{1}{V R} \times \frac{100}{1} = 75$

$\frac{1000}{E} \frac{1}{4} \times \frac{100}{1} = 75$

$E = \frac{250 \times 100}{75}$

E = 333.3N

Ka ìwé ẹ̀kọ́ nípa Simple Machines (JAMB)

Simple Machines

Ibeere 22 Ìròyìn

A force of 500N1 is applied to a steel wire of cross-sectional area 0.2m2, The tensile stress is

2.5x104Nm-2

1.0x102Nm-2

1.0x103Nm-2

2.5x103Nm-2

Awọn alaye Idahun

$S t r e s s = \frac{F o r c e}{A r e a}$
$S t r e s s = \frac{500}{0.2} = 2500$
= 2.5 x 103Nm-3

Ka ìwé ẹ̀kọ́ nípa Elasticity (JAMB)

Ibeere 24 Ìròyìn

The focal length of a concave mirror is 2.0cm. If an object is placed 8.0cm from it, the image is at

2.7m

2.0m

2.3m

2.5m

Awọn alaye Idahun

\frac{1}{U} + \frac{1}{V} = \frac{1}{f}

$\frac{1}{8} + \frac{1}{V} = \frac{1}{2}$

$V = \frac{8}{3}$

$V = 2.7 c m$

Ka ìwé ẹ̀kọ́ nípa Structure Of The Nucleus (WAEC)

Structure Of The Nucleus

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