The text does not specify whether the resistance R of the wire must be kept the same or not: here I assume R must be kept the same.
The relationship between the resistance and the resistivity of a wire is

where

is the resistivity
A is the cross-sectional area
R is the resistance
L is the wire length
the cross-sectional area is given by

where r is the radius of the wire. Substituting in the previous equation ,we find

For the new wire, the length L is kept the same (L'=L) while the radius is doubled (r'=2r), so the new resistivity is

Therefore, the new resistivity must be 4 times the original one.
The heat required to change 1.25 kg of steak is 2825 kJ /kg.
<u>Explanation</u>:
Given, mass m = 1.25 kg, Temperature t = 100 degree celsius
To calculate the heat required,
Q = m
L
where m represents the mass in kg,
L represents the heat of vaporization.
When a material in the liquid state is given energy, it changes its phase from liquid to vapor and the energy absorbed in this process is called heat of the vaporization. The heat of vaporization of the water is about 2260 kJ/kg.
Q = 1.25
2260
Q = 2825 kJ /kg.
Answer:
900J
Explanation:
w =f×s
60×15
=900J
thus the k.e of the body is 900j
Answer: A
Explanation: How large a parachute is (in other words, the parachute's surface area) affects its air resistance, or drag force. ... In the case of these parachutes, the drag force is opposite to the force of gravity, so the drag force slows the parachutes down as they fall.
Answer:
Zero
Explanation:
Given the equation of an ellipse:

The eccentrity of an ellipse is given by:

For a circle, we have

Therefore the eccentricity of a circle is
