Answer:
8.333*10^-6 ohms
Explanation:
Resistivity of a material is expressed as;
p = RA/l
R is the resistance of the material
A is the cross sectional area
l is the length of the material
Given
R = 5 ohms
A = 0.5mm^2
A = 5 * 10^-7m^2
l = 30cm = 0.3m
Substitute into the formula;
p = (5 * 5 * 10^-7m^2)/0.3
p = 25 * 10^-7/0.3
p = 0.0000025/0.3
p = 8.333*10^-6
Hence its resistivity at 20 degrees Celsius is 8.333*10^-6 ohms
Answer:
Work done = -220,000 Joules.
Explanation:
<u>Given the following data;</u>
Mass = 1100kg
Initial velocity = 20m/s
To find workdone, we would calculate the kinetic energy possessed by the car.
Kinetic energy can be defined as an energy possessed by an object or body due to its motion.
Mathematically, kinetic energy is given by the formula;

Where,
- K.E represents kinetic energy measured in Joules.
- M represents mass measured in kilograms.
- V represents velocity measured in metres per seconds square.
Substituting into the equation, we have;
K.E = 220,000J
Therefore, the workdone to bring the car to rest would be -220,000 Joules because the braking force is working to oppose the motion of the car.
Let us consider body moves a distance S due to the force F.
Hence the work by the body W = FS
If the force is not along the direction of displacement,then the work by a body for travelling a distance S will be -
where
is the component of the force along the direction of displacement.


As per the question the power P is given as -




Hence alternative definition of power P = F.V