<span>i think the answer is : Bend the arm at the elbow with the back straight </span>
Answer: The pressure exerted on a surface by an object increases as the surface area of contact decreases.
Explanation:
Pressure measures the amount of force exerted per a given area of an object. From this definition, the surface area of the object and force applied, affects the pressure applied.
As Benny presses his finger against a map, nothing happens to the map because the force applied is affected by the increased surface area of his finger. However as he presses a thumbtack into the map using the same force the tack will probably poke a hole in the map because the small( decreased) surface area of the sharp point of the thumbtack produces a much larger pressure on the map than the area of Benny finger. I hope this helps, thanks!
Answer:
F = 53153.36[N]
Explanation:
In order to solve this problem, we must first use the principle of conservation of energy which is transformed from potential energy to kinetic, in this way we can determine the velocity at which the person enters the water.

where:
m = mass = 100 [kg]
g = gravity acceleration = 9.81 [m/s²]
h = elevation = 9 [m]
v = velocity [m/s]
Now replacing we can determinate the velocity.
![v^{2}=2*g*h\\v=\sqrt{2*g*h}\\v=\sqrt{2*9.81*9}\\v = 13.28[m/s]](https://tex.z-dn.net/?f=v%5E%7B2%7D%3D2%2Ag%2Ah%5C%5Cv%3D%5Csqrt%7B2%2Ag%2Ah%7D%5C%5Cv%3D%5Csqrt%7B2%2A9.81%2A9%7D%5C%5Cv%20%3D%2013.28%5Bm%2Fs%5D)
Then we can calculate the momentum which can be calculated as the product of force by time, this momentum is also equal to the product of mass by velocity.

Now replacing:
F = impact force [N]
t = time = 0.025 [s]
m = 100 [kg]
v = velocity = 13.28 [m/s]
![F*0.025=100*13.28\\F=53153.36[N]](https://tex.z-dn.net/?f=F%2A0.025%3D100%2A13.28%5C%5CF%3D53153.36%5BN%5D)
Use this numbers that you are given and plug them into the formule for net force
Net force= m*a (mass times acceleration)
Therefore the net force is equal to (5.5 kg)*(4.2 m/s^2)= 23.1 N
Answer: Net force= 23.1 N