Good work on solving part a).
b) may look complicated, but it's not too bad.
It says that the body is 25% efficient in converting fat to mechanical energy.
In other words, only 25% of the energy we get from our stored fat shows up
in the physical, mechanical moving around that we do. (The rest becomes
heat, which dissipates into the environment as we keep our bodies warm,
breathe hot air out,and perspire.)
You already know how much mechanical energy the climber needed to lift
himself to the top of the mountain... 2.4x10⁶ joules.
That's 25% of what he needs to convert in order to accomplish the climb.
He needs to pull 4 times as much energy out of fat.
-- Fat energy required = 4 x (2.4 x 10⁶) = 9.6 x 10⁶ joules.
-- Amount stored in 1kg of fat = 3.8 x 10⁷ joules
-- Portion of a kilogram he needs to use = (9.6 x 10⁶) / (3.8 x 10⁷)
Note:
That much of a kilogram weighs about 8.9 ounces ... which shows why it's so
hard to lose weight with physical exercise alone. It also helps you appreciate
that fat is much more efficient at storing energy than batteries are ... that one
kilogram of fat stores the amount of energy used by a 100-watt light bulb, to
burn for 105 hours (more than 4-1/2 days ! ! !)
Answer:
The coefficient of kinetic friction 
Explanation:
From the question we are told that
The length of the lane is 
The speed of the truck is 
Generally from the work-energy theorem we have that
Here N is the normal force acting on the truck which is mathematically represented as
is the change in kinetic energy which is mathematically represented as
=> 
=> 
=> 
=>
<h2>Answer:</h2>
The refractive index is 1.66
<h2>Explanation:</h2>
The speed of light in a transparent medium is 0.6 times that of its speed in vacuum
.
Refractive index of medium = speed of light in vacuum / speed of light in medium
So
RI = 1/0.6 = 5/3 or 1.66
Answer:
35mA
Explanation:
Hello!
To solve this problem we must use the following steps
1. Find the electrical resistance of the metal rod using the following equation
WHERE
α=
metal rod resistivity=2x10^-4 Ωm
l=leght=2m
A= Cross-sectional area
solving
2. Now we model the system as a circuit with parallel resistors, where we will call 1 the metal rod and 2 the man(see attached image)
3.we know that the sum of the currents in 1 and 2 must be equal to 5A, by the law of conservation of energy
I1+I2=5
4.as the voltage on both nodes is the same we can use ohm's law in resitance 1 and 2 (V=IR)
V1=V2
(0.14I1)=2000(i2)
solving for i1
I1=14285.7i2
5.Now we use the equation found in step 3
14285.7i2+i2=5
Answer:
F = 19.375 x 10^-6 N
Explanation:
This problem can be solved by applying Coulomb's Law, which lets us determine the force between two electrically charged particles.
It is defined as
F = (ke * q1 * q2)/ r^2
Where,
ke = is Coulomb's constant ≈ 9×10^9 N⋅m^2⋅C^−2
q1 = 5.0 x 10^-8 C
q2 = 1.0 x 10^-7 C
r = 5 ft = 1,524 m
F = (9×10^9 N⋅m^2⋅C^−2)*(5.0 x 10^-8 C)*(1.0 x 10^-7 C)/ ((1,524 m)^2)
F = (9×10^9 N⋅m^2⋅C^−2)*(5.0 x 10^-8 C)*(1.0 x 10^-7 C)/ ((1,524 m)^2)
F = 19.375 x 10^-6 N
