Answer:
Explanation:
Given
object of mass m is suspended from spring and set in oscillation with time Period T
We know Time period of a mass in oscillation is given by

where k=spring constant
When mass m is replaced by a mass of 2 m time period is given by



i.e. New time period becomes
times of previous one
Answer:9.34 A/s
Explanation:
Given
radius of solenoid 
Emf induced 
no of turns per meter n=450
we know Induced EMF is given by

Magnetic Field is given by

thus 
Area of cross-section
where
solving integration we get

where r=distance from axis
R=radius of Solenoid



Incomplete question.The complete question is attached below as screenshot along with figure
Answer:

Force is repulsive
Explanation:
Given data
Current I₁=5.00A
Current I₂=2.00A
Length L=1.20 m
Radius r=0.400m
To find
Force F
Solution
As the force is repulsive because currents are in opposite direction
From repulsive force we know that:

Substitute the given values