Answer:
the signs of heat and work are; -Q and -W
Explanation:
The first law of thermodynamics is given by; ΔU = Q − W
where;
ΔU is the change in internal energy of a system,
Q is the net heat transfer (the sum of all heat transfer into and out of the system)
W is the net work done (the sum of all work done on or by the system).
Now, The system in this case is the tire and since the air gets warmer, heat must have left the system. Therefore Q is negative (-Q).
Since work is done by the system, W remains negative.
Thus, the signs of heat and work are; -Q and - W
Answer:
B. counterclockwise
Explanation:
We can solve the problem by using the right-hand rule:
- put your thumb finger of the right hand in the same direction of the current in the wire (upward)
- wrap the other fingers around the thumb
- the direction of the other fingers will give the direction of the magnetic field lines
By doing these steps, we see that the other fingers form concentric circles in a counterclockwise direction (seen from above), so this is the direction of the magnetic field lines.
Answer:
B. Resistivity
Explanation:
Resistance offered by a substance of unit area per unit length.
Answer:
a) 
, b) 
Explanation:
a) The equation for vertical velocity is obtained by deriving the function with respect to time:
The velocities at given instants are, respectivelly:
