If the gears are of different sizes, they can be used to increase the power of a turning force. The smaller wheel turns more quickly but with less force, while the bigger one turns more slowly with more force. Cars and bicycles use gears to achieve amazing speeds our bodies could never match without help.
The first law of thermodynamics says that the variation of internal energy of a system is given by:

where Q is the heat delivered by the system, while W is the work done on the system.
We must be careful with the signs here. The sign convention generally used is:
Q positive = Q absorbed by the system
Q negative = Q delivered by the system
W positive = W done on the system
W negative = W done by the system
So, in our problem, the heat is negative because it is releaed by the system:
Q=-1275 J
while the work is positive because it is performed by the surrounding on the system:
W=+855 J
So, the variation of internal energy of the system is
Answer:
Friction does not oppose motion, it oppose relative motion.
Explanation:
static friction opposes relative motion
You said T = mg + ma
Subtract mg
from each side: T - mg = ma
Divide each side by m : a = (T-mg) / m
or a = T/m - g
Answer:
KE = 11,719 J
Explanation:
KE = ½ mv²
KE = ½ (1.5 kg) (125 m/s)²
KE = 11,719 J