Answer:652.05 J
Explanation:
Given
Weight of lifter 
vertical distance move 
Work done in lifting the weight is equal change in Potential Energy of weight
Change in Potential Energy 

therefore work done is equal to
Question 9 is 100 N.
Question 10 is No, the bike's motion is not changing so it could be at rest or moving at a constant velocity.
Question 11 is Be doubled.
Question 12 is Ella is correct.
Hope i helped.
recoils and must be tethered or he's gone.
Answer:
α = - 1.883 rev/min²
Explanation:
Given
ωin = 113 rev/min
ωfin = 0 rev/min
t = 1.0 h = 60 min
α = ?
we can use the following equation
ωfin = ωin + α*t ⇒ α = (ωfin - ωin) / t
⇒ α = (0 rev/min - 113 rev/min) / (60 min)
⇒ α = - 1.883 rev/min²
Here as we know that there is no loss of energy
so we can say that maximum kinetic energy will become gravitational potential energy at its maximum height
So here we have

here we have
v = 20 m/s
m = 8000 kg
now from above equation we have



so maximum height is 20.4 m