The mechanical work done by the sprinter during this time will be 4537.5 J , the average power the sprinter must generate will be 907.5 W and if the sprinter converts food energy to mechanical energy with an efficiency of 25% then he will be burning calories at 54.20 calories per second.
Work in physics is the energy that is transferred to or from an item when a force is applied along a displacement. It is frequently described in its most basic form as the result of force and displacement.
The quantity of energy moved or transformed per unit of time is known as power in physics. The watt, or one joule per second, is the unit of power in the International System of Units.. A scalar quantity is power.
Given 75-kg sprinter accelerates from rest to a speed of 11.0 m/s in 5.0 s.
So let,
m = 75 kg
v = 11.0 m/s
t = 5.0 s
So the mechanical work done by the sprinter during this time will be as follow:
W = 0.5 mv²
W = 0.5 (75)(11)²
W = 4537.5 J
The average power the sprinter must generate will be as follow:
Power(P) = W / t
P = 4537.5/5
P = 907.5 W
Only 25% is absorbed. So, the sprinter only absorbed 226.875 J per second which is equal to 54.20 calories per second.
Hence mechanical work done by the sprinter during this time will be 4537.5 J , the average power the sprinter must generate will be 907.5 W and if the sprinter converts food energy to mechanical energy with an efficiency of 25% then he will be burning calories at 54.20 calories per second.
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Answer:
The correct option is a
Explanation:
The alpha particle has the lowest penetrating power of the trio of alpha, beta and gamma particles and can be stopped by a sheet of paper and hence cannot penetrate a human skin. Beta particle has a higher penetrating power than alpha particle (some of it penetrates the human skin and some do not) while the gamma particle has the highest penetrating power (with all of it penetrating the human skin).
From the above description, it can be deduced that the alpha particle will stay and interact with the hand (because of its low penetrating power) as the remaining particles move through the skin.
Answer:
<h2>32m/s^2</h2>
Explanation:
We want to find the acceleration based on the given data
Given
distance s=400m
time t= 5s
u= 0m/s since it started from rest
We apply the following expression
s=ut+1/2at^2
substituting we have
400=0*5+1/2*a(5)^2
400=25a/2
cross multiply
25a=400*2
25a=800
divide both sides by 25 we have
a=800/25
a=32m/s^2
The acceleration is 32m/s^2
Answer;
D. ocean currents might change course.
Explanation;
Ocean currents are the directed movements of water in the ocean and can be caused by wind (for currents closer to the surface) and temperature, salinity, or density differences (currents deeper in the ocean). Ocean currents help to warm or cool certain parts of the earth by carrying warmer water northward or cooler water toward the equator.
Climate change can have a vast effect on ocean currents because of the change in temperature it causes, which results in change in ocean water temperatures and a subsequent distortion in current flow.
To solve the problem it is necessary to apply conservation of the moment and conservation of energy.
By conservation of the moment we know that
Where
M=Heavier mass
V = Velocity of heavier mass
m = lighter mass
v = velocity of lighter mass
That equation in function of the velocity of heavier mass is
Also we have that 
On the other hand we have from law of conservation of energy that
Where,
W_f = Work made by friction
KE = Kinetic Force
Applying this equation in heavier object.
Here we can apply the law of conservation of energy for light mass, then
Replacing the value of 
Deleting constants,
