Answer:
a) their potential energy increases.
Explanation:
Ohm's Law is
R= V/I
Where R= Resistance
V= potential difference or potential energy
I= current or conduction electron flow rate
Clearly R and V are directly proportional i-e Potential energy increases with resistance.
Answer:
We have to show surface area 
,with few conditions that is by considering Force 
and Pressure 
to be respectively.
Explanation:
The atmospheric pressure is 
on Earth's surface.
The magnitude of the force exerted on a person by the atmosphere is 
.
Now to calculate surface area we can find it from 
and re-arranging it to.
So plugging the values,
Surface area 
Hence from the above calculations we can say that surface area is 
.
So the surface area of an average person can be said to have , using the concept of pressure and force.
Here is my step-by-step-work. Let me know if you have any questions! :)
Answer:
The shortest braking distance is 35.8 m
Explanation:
To solve this problem we must use Newton's second law applied to the boxes, on the vertical axis we have the norm up and the weight vertically down
On the horizontal axis we fear the force of friction (fr) that opposes the movement and acceleration of the train, write the equation for each axis
Y axis
N- W = 0
N = W = mg
X axis
-Fr = m a
-μ N = m a
-μ mg = ma
a = μ g
a = - 0.32 9.8
a = - 3.14 m/s²
We calculate the distance using the kinematics equations
Vf² = Vo² + 2 a x
x = (Vf² - Vo²) / 2 a
When the train stops the speed is zero (Vf = 0)
Vo = 54 km/h (1000m/1km) (1 h/3600s)= 15 m/s
x = ( 0 - 15²) / 2 (-3.14)
x= 35.8 m
The shortest braking distance is 35.8 m
