Answer:
the heaviest barbell that could be lifted is 390.6kg
Explanation:
Hello!
To solve this question you must follow the following steps
1. Find the amount of energy that can transform the body into motion, this is achieved by multiplying the breakfast consumed by the percentage of energy conversion.

2. We use the equation that defines the work done by a body that has weight when it is lifted, this is defined by the product of mass by gravity by height.
W=mgh
where
W=work=6898.5J
m=mass
g=gravity=9.81m/s^2
h=height=1.8m
now we solve for mass, and use the values.

the heaviest barbell that could be lifted is 390.6kg
<span>No, there is no control group because each group is treated under test conditions.</span>
The system's tension is 616 N and acceleration is 5.6 
<u>Explanation:</u>
From newton’s second law of motion which state that net force acting on a body is product of mass of a body and acceleration of a body which is given as,

Where,
is net force acting on body
is mass of body
a is acceleration of body
Given values
Table mass (m) = 30 kg
Hanging mass (m) = 40 kg

Put the value for m = hanging mass = 40 kg and
, we get

The tension in the ropes, 
Here, m as hanging mass
T = tension, N or 
m = mass, kg
g = gravitational force, 
a = acceleration, 

According to the Law of Universal Gravitation, the gravitational force is directly proportional to the mass, and inversely proportional to the distance. In this problem, let's assume the celestial bodies to be restricted to the planets and the Sun. Since the distance is specified, the other factor would be the mass. Among all the celestial bodies, the Sun is the most massive. So, the Sun would cause the strongest gravitational pull to the satellite.