The ball's horizontal and vertical velocities at time
are


but the ball is thrown horizontally, so
. Its horizontal and vertical positions at time
are


The ball travels 22 m horizontally from where it was thrown, so

from which we find the time it takes for the ball to land on the ground is

When it lands,
and


Answer:
400 N
Explanation:
By the law of friction,

is the maximum frictional force,
is the coefficient of friction and
is the reaction on the refrigerator. On a horizontal surface, the reaction is equal to the weight of the refrigerator.


While not moving, the fricition on the refrigerator is static friction. So, 

This is the maximum frictional force and is more than the applied horizontal force of 400 N. Frictional force cannot be more than the applied force, else it would actually pull the refrigerator backwards (a strange thing, if it were to happen). It is equal to the extent of the applied force because the applied force is not enough to overcome the maximum.
Hence the frictional force is 400 N.
PS: Note that we do not use the coefficient of kinetic friction because applied force could not overcome the static friction.
Answer:
4
Explanation:
We know that intensity I = P/A where P = power and A = area through which the power passes through.
Now, let the initial intensity of the speaker be I₀ and its initial power be P₀. Since the intensity is increased by a factor of 4, the new intensity be I and new power be P.
So, I = P/A and I₀ = P₀/A
Now, if I = 4I₀,
P/A = 4P₀/A
P = 4P₀
Now, energy E = Pt, where t = time. So, P = E/t and P₀ = E₀/t
Substituting P and P₀ into the equation, we have
P = 4P₀
E/t = 4E₀/t
E = 4E₀
Since the energy is four times the initial energy, the energy output increases by a factor of 4.
Answer:
Too much screen time can be a bad thing: Children who consistently spend more than 4 hours per day watching TV are more likely to be overweight. Kids who view violent acts on TV are more likely to show aggressive behavior, and to fear that the world is scary and that something bad will happen to them. When we considered the whole television chain of production, distribution and consumption, we found that the largest environmental impact associated with a television programme was not the energy consumed in making it, but the energy used by the millions of televisions, set-top boxes and other consumer devices involved
Explanation: