Physics 2008 | Study Mode

Question 41

THe diagram above shows a plank RS pivoted its center of gravity O and is in equilibrium with the weight P and Q. If a weight 2P is added to P the plank will be in equilibrium again by Phy-question-image

moving Q nearer to O

moving P nearer to O

addding a weight Q to Q

moving P further away from O

Explanation

If 2P is added P, the beam will bend at R side. So to keep it in equilibrium. P should be moved nearer to 0

Correct option: B

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Question 42

The efficiency of the pulley system shown above is 80%. find the effort E required to lift the load of 1200N Phy-question-image

275N

325N

375N

573N

Explanation

VR = No. of pulleys = 4
Efficiency = ^M.A/_V.R x 100% = load
Effort x 100%_V.R
80 = 1200 x 100 x 1100__Effort4
Effort = 1200 x 100 = 375N_80 x 4

Correct option: C

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Question 43

The diagram above is the heating curve for a solid QR is the Phy-question-image

melting region

boiling region

sublimation region

evaporating process

Explanation

At melting point there is no change temperature

Correct option: A

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Question 44

The above figure shows the motion of a progressive wave along a string. The particle motion of the medium is in direction Phy-question-image

parallel to OX

parallel to OY

60^o to OX

60v to OY

Explanation

Particles of the transmitting medium in transverse wave oscillate in a direction perpendicular to the propagation of the wave

Correct option: B

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Question 45

If a convex lens of focal length 12cm is used to produce a real image four times the size of the object, how far from the lens must the object be placed?

10 cm

15 cm

20 cm

25 cm

Explanation

Magnifications = ^V/_U = 4
V = 4U
¹/_V + ¹/_U = ¹/_f
¹/_4u + ¹/_U = ¹/₁₂
⁵/_4U = ¹/₁₂
4U = 12 x 5 = 60
U = 15 cm

Correct option: B

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Question 46

Find the effective resistance in the diagram above Phy-question-image

Explanation

The resistors are in series
Reff = R₁ + R₂ + .....
= 4 + 4 + 4 + 4 + 4 + 4 = 24

Correct option: D

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Question 47

Given the inductor of inductance 5mH, 10mH and 20mH connected in series, the effective inductance is Phy-question-image

0.35mH

3.50mH

2.90mH

35.0mH

Explanation

Left = L₁ + L₂ + L₃
= 5mH + 10mH + 20mH = 35mH

Correct option: D

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Question 48

If electron are accelerated from rest through a potential difference of 10kv, what is the wavelength of the associated electron
[m = 9.1 x 10^-31kg, e = 1.6 x 10^-19C, h = 6.6 x 10^-34js]

1.22 x 10^-11m

3.87 x 10^-10m

2.27 x 10¹¹m

2.27 x 10¹⁴m

Explanation

=	__h
	(2evm)

=	____6.6 x 10^-34
	(2 x 1.6x10^-19 x 10000 x 9.1x10^-34)

1.223 x 10^-11m

Correct option: A

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Question 49

14	N +	4	He	17	O + X
7		2		8

In the equation above, the particles X is

a proton

a neutron

an - particle

a - particle

Explanation

for the conversion of mass 14 + 4 = 17 + x
X = 18 - 17 = 1
for conservation pf charge:7 + 2 = 8 + y
y = 9 - 8 = 1
Thus, the element is ₁¹X which is equal to hydrogen nucleus ( proton)

Correct option: A

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Question 50

Find the median of 4, 1, 4, 1, 0, 4, 4, 2 and 0