Using aluminum wire(2.82x10^-8 ohm) of diameter 1.60mm, you want to wind a resistor that will dissipate 25.0 W when 25.0 V is applied across it . What length( in m) of wire is needed?

4565 meters

Explanation:

W = V²/R

25 = (25)²/R

R = 25 ohm

R = (pl)/A

l = 4565 meters approximately

the minimum constant speed at which she can catch the train is 2.7 m/s

given:

acceleration = 0.6

time = 4.5 s

to find:

velocity = ?

formula used:

from 1st kinematic equation we get,

v = u + at

u = initial speed of train = 0 m/s

v = final speed of the train

a = acceleration of the train

t = time

solution:

from 1st kinematic equation we get,

v = u + at

u = initial speed of train = 0 m/s

v = final speed of the train

a = acceleration of the train

t = time

v = 0 + (0.6 × 4.5)

v = 2.7 m/s

the minimum constant speed at which she can catch the train is 2.7 m/s