Answer:
4.2 m
Explanation:
Note: If energy is conserved, i.e no work is done against friction
Work input = work output.
Work output = Force output × distance,
Work input = force input × distance moved moved.
Therefore,
input force×distance moved = output force × distance moved........................Equation 1
Given: input force = 80 N, output force = 240 N, output distance = 1.4 m
Let input distance = d
Substitute into equation 1
80×d = 240×1.4
80d = 336
d = 336/80
d = 4.2 m.
Thus the rope around the pulley must be pulled 4.2 m
Answer:
Buttery popcorn contained in a large 1 liter bowl has a mass of about 50 mg and about 650 calories.
Explanation:
Liter is the most appropriate unit to measure a bowl. Usually 1 liter of liquid has a mass of 1000 gram. Since popcorn is something lightweight and only a few can fill the bowl quickly so 50 mg makes perfect sense with 1 liter of bowl and 650 calories in buttery popcorn.
Recall that
where 
and 
are the initial and final velocities, respecitvely; 
is the acceleration; and 
is the change in position.
So we have
(Normally, this equation has two solutions, but we omit the negative one because the car is moving in one direction.)
