• We need your support!

    We are currently struggling to cover the operational costs of Xtremepapers, as a result we might have to shut this website down. Please donate if we have helped you and help make a difference in other students' lives!
    Click here to Donate Now (View Announcement)

Physics MCQs thread.

Messages
1,800
Reaction score
1,800
Points
173
A force of 1000 N is needed to lift the hook of a crane at a steady velocity. The crane is then used
to lift a load of mass 1000 kg at a velocity of 0.50 m s–1.
How much of the power developed by the motor of the crane is used in lifting the hook and the
load? Assume that the acceleration of free fall g is equal to 10 m s–2.

A 5.0 kW
B 5.5 kW
C 20 kW
D 22 kW


Why is the answer B??
 
Messages
755
Reaction score
159
Points
53
arlery said:
A force of 1000 N is needed to lift the hook of a crane at a steady velocity. The crane is then used
to lift a load of mass 1000 kg at a velocity of 0.50 m s–1.
How much of the power developed by the motor of the crane is used in lifting the hook and the
load? Assume that the acceleration of free fall g is equal to 10 m s–2.

A 5.0 kW
B 5.5 kW
C 20 kW
D 22 kW


Why is the answer B??

power= Fv
total force is 1000 + (1000*10)
so power is 11000*0.5
5.5kw
 
Messages
1,800
Reaction score
1,800
Points
173
Can any one please help me with this??
 

Attachments

  • untitled.PNG
    untitled.PNG
    41.5 KB · Views: 42
Messages
286
Reaction score
4
Points
0
Two springs P and Q both obey Hooke’s law. They have spring constants 2k and k respectively.
The springs are stretched, separately, by a force that is gradually increased from zero up to a
certain maximum value, the same for each spring. The work done in stretching spring P is WP,
and the work done in stretching spring Q is WQ.
How is WP related to WQ?
A WP =  0.25WQ B WP = 0.5 WQ C WP = 2WQ D WP = 4WQ
 
Messages
426
Reaction score
4
Points
0
arlery said:
Can any one please help me with this??
lol nice question, consider ur eyes as the positive plate and the question as the negative plate. u should get it as D
 
Messages
1,800
Reaction score
1,800
Points
173
A source of e.m.f. of 9.0 mV has an internal resistance of 6.0 Ω.
It is connected across a galvanometer of resistance 30 Ω.
What will be the current in the galvanometer?
A 250 μA
B 300 μA
C 1.5 mA
D 2.5 mA

Why is the answer A?
 
Messages
257
Reaction score
4
Points
28
Hateexams93 said:
Two springs P and Q both obey Hooke’s law. They have spring constants 2k and k respectively.
The springs are stretched, separately, by a force that is gradually increased from zero up to a
certain maximum value, the same for each spring. The work done in stretching spring P is WP,
and the work done in stretching spring Q is WQ.
How is WP related to WQ?
A WP =  0.25WQ B WP = 0.5 WQ C WP = 2WQ D WP = 4WQ
hey first find f for both using f=kx x iz same for both
then use wd =1/2fx
 
Messages
257
Reaction score
4
Points
28
A source of e.m.f. of 9.0 mV has an internal resistance of 6.0 Ω.
It is connected across a galvanometer of resistance 30 Ω.
What will be the current in the galvanometer?
A 250 μA
B 300 μA
C 1.5 mA
D 2.5 mA
any one????
 
Messages
426
Reaction score
4
Points
0
yubakkk said:
A source of e.m.f. of 9.0 mV has an internal resistance of 6.0 Ω.
It is connected across a galvanometer of resistance 30 Ω.
What will be the current in the galvanometer?
A 250 μA
B 300 μA
C 1.5 mA
D 2.5 mA
any one????
TOTAL resistance = 30 + 6 = 36 ohms
e.m.f = 9 mV = 9 x 10^-3 V

V=IR

I = 9 x 10^-3 / 36 = 2.5 x 10^-4 = 250 μA
 
Top