We can first calculate the net force using the given information.
By Newton's second law, F(net) = ma:
F(net) = 25 * 4.3 = 107.5
We can now calculate the frictional force, f, which is working against the applied force, F(app) (this is why the net force is a bit lower):
f = F(net) - F(app) = 150 - 107.5 = 42.5 N
Now we can calculate the coefficient of friction, u, using the normal force, F(N):
f = uF(n) --> u = f/F(N)
u = 42.5/[25(9.8)]
u = 0.17
First of all, we can find the mass of the person, since we know his weight W:

And so

We know for Newton's second law that the resultant of the forces acting on the person must be equal to the product between the mass and the acceleration a of the person itself:

There are only two forces acting on the person: his weight W (downward) and the vincular reaction Rv of the floor against the body (upward). So we can rewrite the previous equation as

We know the acceleration of the system,

(upward, so with same sign of Rv), so we can solve to find the value of Rv, the normal force exerted by the elevator's floor on the person:
To solve this problem it is necessary to use the given proportions of power and energy, as well as the energy conversion factor in Jules to Calories.
The power is defined as the amount of energy lost per second and whose unit is Watt. Therefore the energy loss rate given in seconds was


The rate of energy loss per day would then be,


That is to say that Energy in Jules per lost day is 5356800J
By definition we know that 
In this way the energy in Cal is,


The number of kilocalories (food calories) must be 1279.694 KCal
Answer:

Explanation:
As we know that water from the fountain will raise to maximum height

now by energy conservation we can say that initial speed of the water just after it moves out will be




Now we can use Bernuolli's theorem to find the initial pressure inside the pipe



Answer:
Amplitude, A = 0.049 meters
Explanation:
Given that,
A harmonic wave travels in the positive x direction at 6 m/s along a taught string. A fixed point on the string oscillates as a function of time according to the equation :
.......(1)
The general equation of a wave is given by :
.......(2)
A is amplitude of wave
On comparing equation (1) and (2) we get :
A = 0.049 meters
So, the amplitude of the wave is 0.049 meters.