Answer:
U = 1000 J
Explanation:
By the conservation of energy, potential energy is converted into kinetic energy when the ball falls from a height.

U = Energy (in Joules)
m = mass (in kg)
v = velocity in (m/s)
g = acceleration due to gravity (in m/s^2)
h = height (in m)
Let's use
as we have the values given.


Answer:
c. may be accompanied by the sound of explosively expanding hot air, called thunder.
Explanation:
Lightning is a discharge which is due to the reaction between oppositely charged charges in the clouds, or between clouds base and the Earth surface.
The motion of the cloud causes charging of clouds by friction, thus the reaction between opposite charges (jumping of charges from one cloud to another) in the cloud can lead to lightning. Also, oftentimes the bottom of a cloud is negatively charged so that this is attracted to the positive charge on the earth surface. Thus leading to a discharge called lightning.
Thus in the given question, the appropriate option is C. This implies that, lightning may be accompanied by the sound of explosively expanding hot air, called thunder.
Answer:
Explanation:
given,
mass of block = 3 kg
spring constant k = 500 N/m
kinetic friction coefficient µk = 0.6
speed of block = 5 m/s
F = µk N
F = 0.6 x 3 x 9.8
F = 17.64 N
using energy conservation


250 x² + 17.64 x - 37.5 = 0
on solving
x = 0.354 m
graph is attached below
For all antinodal positions we know that

now we also know the relation between phase difference and path difference

now we will have

now from above equation we will have

now for the first anti node position
N = 1

Option D is correct
Answer:
Magnetic field will be equal to 
Explanation:
We have given velocity of proton 
Magnetic force experienced by proton 
Charge on proton 
Angle between field and velocity 
Force in magnetic field is equal to 
So 

So magnetic field will be equal to 