Difference in energy between the exicted states and ground states
Answer:
The period would decrease by sqrt(2)
Explanation:
The restoring force is given by,
F = -kx
According to Newton's second law of motion,
ma = -kx
ma + kx = 0
The time period is given by,
T =
Where
is the angular velocity and it is given by,
= 
Now if the spring constant is doubled then,

Thus,
=



Thus, The period would decrease by sqrt(2).
Hence, option D is correct.
Answer:
C. is responsible for sliding friction and contact forces
Question four bulbs A,B,C and D are connected in a circuit shown in the figure below, the letters X, Y and Z represent three switches. Which switch is used to operate switch A separately?
Answer: x
Answer:
22.2 W
Explanation:
First of all, we calculate the work done by moving the wagon, using the formula:

where
F = 20 N is the magnitude of the force
d = 1000 m is the displacement of the wagon
is the angle between the direction of the force and of the displacement (assuming the force is applied in the direction of motion)
Substituting, we find

Now we can find the power generated, which is equal to the ratio between the work done and the time taken:

where
W = 20,000 J
t = 15 min = 900 s
Substituting,

And the same value in Joules/second (remember that 1 Watt = 1 Joule/second)