Answer:
Work done to pull the piano upwards is 401250 J
Explanation:
Work is done against the gravity to pull the piano upwards
So here we can say that work done is

here we know that

also we know that
H = 75 m
now we have


I would say Conduction because you are touching the cookie sheet, even though it is hot (so heat) you are physically touching it so it would not be radiation
Answer:
KE = 2.03 J
Explanation:
After impact, the kinetic energy of the bullet+block will convert to potential energy
½mv² = mgh
v = √(2gh) = √(2(9.81)(0.00500) = 0.0981 m/s
conservation of momentum during the collision
0.015u + 2.50(0) = (2.50 + 0.015)(0.0981)
u = 16.4481 m/s
KE = ½mv² = ½(0.015)16.4481² = 2.0290499...
KE = 2.03 J