An electric heater used to boil small amounts of water consists of a 15-Ω coil that is immersed directly in the water. It operat
1 answer:
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a) Solids keep shape, liquids take shape of containers but don't spill, gases take container's shape and spill out
b) if you heat gas, speed of its molecules will increase and they'll push the container's walls stronger, so the pressure will increase when the container heated
c) Heat flows from warmer to colder bodies
d) For monatomic gases it's U=1.5nRT only, molecular gas has bonds between atoms so total internal energy increases
e) Of gases
f) m/s
g) U=5/2*nRT=37830.85 J
Answer
(C).
When there is an angle between the two directions, the cosine of the angle must be considered.
Step by step Solution
The work done by a force is defined as the product of the force and the distance traveled in the direction of motion.
The first answer "Only the component of the force perpendicular to the motion is used to calculate the work" is wrong because, the force perpendicular to motion does no work.
The second choice "If the force acts in the same direction as the motion, then no work is done" is wrong because the work in the direction of the force is .
Fourth answer "A force at a right angle to the motion requires the use of the sine of the angle" is wrong because the meaning that there is no work done in the direction perpendicular to the motion.
The third answer" When there is an angle between the two directions, the cosine of the angle must be considered." is correct because the work is calculated using the force in the direction of the motion. The magnitude of this force is
Answer:
The time where the avergae speed equals the instaneous speed is T/2
Explanation:
The velocity of the car is:
v(t) = v0 + at
Where v0 is the initial speed and a is the constant acceleration.
Let's find the average speed. This is given integrating the velocity from 0 to T and dividing by T:
v_ave = v0+a(T/2)
We can esaily note that when <u><em>t=T/2</em></u><u><em> </em></u>
v(T/2)=v_ave
Now we want to know where the car should be, the osition of the car is:
Where x_A is the position of point A. Therefore, the car will be at:
<u><em>x(T/2) = x_A + v_0 (T/2) + (1/8)aT^2</em></u>