Heat because in a machine heat must come out to follow the law of conservation of energy
Answer : Cat will reach tree first.
Explanation :
It is given that,
Total distance between dog and tree is 30 yards. The cat has 10 yards lead. So, the distance between cat and tree is 20 yards.
Speed of cat is 6 Yards/ sec.
Speed of dog is 8 Yards/sec.
speed of cat is, 


Now, speed of dog is, 


It is clear that, cat is taking less time as compared with dog. So, the cat will reach tree first.
Answer:

Explanation:
The work done on the object at rest is all converted into kinetic energy, so we can write

Or, re-arranging for v,

where
v is the final speed of the object
W is the work done
m is the object's mass
If the work done on the object is doubled, we have W' = 2W. Substituting into the previous formula, we can find the new final speed of the object:

So, the new speed of the object is
.