Answer:

0.3619sec
Explanation:
Given that
Mass,m=148 g
Length,L=13 cm
Velocity,u'(0)=10 cm/s
We have to find the position u of the mass at any time t
We know that

Where 

u(0)=0
Substitute the value

Substitute u'(0)=10


Substitute the values

Period =T = 2π/8.68
After half period
π/8.68 it returns to equilibruim
π/8.68 = 0.3619sec
Answer:

Explanation:
When we push the box from the bottom of the incline towards the top then by work energy theorem we can say that
Work done by all the forces = change in kinetic energy of the system

here we know that

also we know that the length of the incline is given as

now we have

so we have

Answer:
(iv), (v), (vi) would be incorrect.
Explanation:
(iv) Force isn't transferred from one colliding object to another, but momentum can be.
(v) An object doesn't stop immediately a force stops acting on it. Think of a thrown ball.
(vi) For an object not to move, it means that the net force on the object is zero, and not necessarily that there are no forces acting on the object. For example, an object could be pushed on one side, and be pushed on the other side with an equal force in the opposite direction. The forces would cancel each other and the net force would be zero.
The rest should be correct.
<span>Make the surfaces smoother. Rough surfaces produce more friction and smooth surfaces reduce friction
Lubrication is another way to make a surface smoother
Make the object more streamlined
Reduce the forces acting on the surfaces
<span>Reduce the contact between the surfaces.</span></span>
Sunspots are spot like structure on the surface of sun, they are created due to geomagnetic flux which inhibits the convection of heat waves thus reducing the temperature of spot with some factor