Answer:
Velocity, v = 2.50 m/s
Explanation:
Given that,
Mass of the ball, m = 7.26 kg
Height above the ground, h = 2.1 m
Mechanical energy of the ball, T = 172.1 J
To find,
The velocity of the ball at the given point.
Solution,
The sum of potential energy and the kinetic energy is called the mechanical energy of an object. It is given by :

K is the kinetic energy
P is the potential energy

On rearranging the above equation,


v = 2.50 meters
Therefore, the velocity of the ball at the given point is 2.50 m/s.
Answer:
The speed of ejection is 
Solution:
As per the question:
Magnetic field density, B = 0.4 T
Density of the material in the sunspot, 
Now,
To calculate the speed of ejection of the material, v:
The magnetic field energy density is given by:

This energy density equals the kinetic energy supplied by the field.
Thus


where
m = mass of the sunspot in
= 


The force tending to lift the load (vertical force) is equal to <u>22.5N.</u>
Why?
Since the boy is pulling a load (150N) with a string inclined at an angle of 30° to the horizontal, the total force will have two components (horizontal and vertical component), but we need to consider the given information about the tension of the string which is equal to 105N.
We can calculate the vertical force using the following formula:

Hence, we can see that <u>the force tending to lift the load</u> off the ground (vertical force) is equal to <u>22.5N.</u>
Have a nice day!
Let
be the direction the swimmer must swim relative to east. Then her velocity relative to the water is

The current has velocity vector (relative to the Earth)

The swimmer's resultant velocity (her velocity relative to the Earth) is then


We want the resultant vector to be pointing straight north, which means its horizontal component must be 0:

which is approximately 41º west of north.
Correct option: A
An object remains at rest until a force acts on it.
As the water moves faster, it applies greater force on the sediment, which over comes the frictional forces between the bed and the sediment. So, when the river flows faster, more and larger sediment particles are carried away. When the flow slows down, the river couldn't apply enough force on the larger sediments which can overcome the frictional force between the sediment and the river bed. So, the net force on the heavier particles become zero. Hence, the heavier particles of the load will settle out.