Tonya is thinking about the topic presented in the text, "Do opposites really attract?" Which of her thoughts is an example of c
1 answer:
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Complete question:
A fireman of mass 80 kg slides down a pole. When he reaches the bottom, 4.2 m below his starting point, his speed is 2.2 m/s. By how much has thermal energy increased during his slide?
Answer:
The thermal energy increased by 3,099.2 J
Explanation:
Given;
mass of the fireman, m = 80 kg
initial position of the fireman, hi = 4.2 m
final speed, v = 2.2 m/s
The change in the thermal energy is calculated as;
ΔE + (K.Ef - K.Ei) + (Uf - Ui) = 0
where;
ΔE is the change in the thermal energy
K.Ef is the final kinetic energy
K.Ei is the initial kinetic energy
Uf is the final potential energy
Ui is the initial potential energy
Answer:
a) speed when Jack sees the pot : 12.92 meters per second
b) height difference 163.115 meters
Explanation:
First to calculate te initial speed we use the acceleration formula:
a= v1-v0/t
Acceleration being gravity's acceleration (9.8 m/s^2)
v1 being the speed when Jill sees the pot
v0 when Jack sees it
and t the time between
Solving for v0 it would be
v1 - a*t = v0
replacing
For the second question we use the position formula setting y0 and t0 as the position and time when jack sees the pot. (and setting the positive axis downward I.E. one meter below jack would be 1m not -1m)
The formula is
replacing
Use the relation between electric force and electric field and the concept of gravitational force to calculcate the electric field. The electric force is given by
And the gravitational force is
For the ball to float above the ground, the magnitude of electric force on the ball must be equal to the magnitude of the gravitational force. That is must be a equilibrium condition, so,
Replacing the values we have that,
Therefore the electric field magnitude that would cause the ball to float above the ground is