Answer:

Explanation:
The resistance of a wire is given by the equation:

where
is the resistivity of the material
L is the length of the wire
A is the cross-sectional area of the wire
In this problem, we have a wire of platinoid, whose resistivity is

The length of the wire is
L = 7.0 m
And its radius is
, so the cross-sectional area is

Solving for R, we find the resistance of the wire:

Answer:
3 m/s east
Explanation:
The velocity of the car is given by:

where
d is the displacement
t is the time taken
The displacement of the car does not depend on the path of the car, but just on it the difference between its final position and its starting position, so it is equal to 15 metres east. The time taken is 5 seconds, therefore the velocity is equal to

and the direction is east.
-A photon travels, on average, a particular distance, d, before being briefly absorbed and released by an atom, which scatters it in a new random direction.
-Given d and the speed of light, c, you can figure out the average time step and space step size (how often the photon “steps” and how far it “steps” each time).
-The size of the Sun is figured in terms of step size. Some surprisingly tricky math happens, involving “Brownian motion” and probabilities. Finally,
-The average time it would take to get to the surface of the Sun is found.
The solution for this is:
Work done = force * distance = m*a*d and power = energy/time
The vo=0 and vf = 25 m/s and t=7 sec. This gives...
3.6 m/s^2 as acceleration and d=87.5 meters and thus F=ma= 5400 N.
Energy = 5400*87.5 = 4.7E5 Joules (2 sig. figs) and Power = 67,500 Watts or 90 HP (2 sig. figs again).