Answer:
Gravity
Explanation:
Gravity applies a constant downward force on the cars. The coaster tracks serve to channel this force — they control the way the coaster cars fall. If the tracks slope down, gravity pulls the front of the car toward the ground, so it accelerates
Answer:
312 kJ
Explanation:
The thermal energy contained in a cubic meter of air at room temperature (20 C) and one atmosphere (101 kPa) would be.
H = Cv * T + p * V
Being
Cv: specific heat of air at constant volme (0.72 kJ/(kg*K))
T: temperature in absolute scale (20C is 293 K)
Then:
H = 0.72 * 293 + 101 * 1 = 312 kJ
The only way to extract thermal energy from a body and turn it into useful work (such as charging a phone) is to exchange heat with it and a another colder body. So, with just the air at room temperature it is impossible to extract its heat energy.
Answer:
Percentage change in tension is 3.8%
Explanation:
We have given initially frequency = 440 Hz
Let tension in the string at this frequency is
Now second frequency is
Frequency in string is given by
From the relation we can say that
Percentage change in tension is equal to
%
So percentage change in tension is 3.8%
Answer: No, the student does not do any work on the wall.
Explanation: The work is defined as the movement of an object done/caused by a force.
And it can be calculated as:
W = F*d
where W is work, F is force and d is the displacement of the object
In this case, the student is applying force on the wall, so we have the first part, but we also know that the wall does not move, so in this case, d = 0, which would imply that the work applied to the wall must be equal to zero
(because W = F*0 = 0)
So the answer is no, the student does not do any work on the wall.