Another name for these two words is "constant" and you want to have a "constant", because you want something to compare your experimental group to, to see whether data had changed or not. So you have placebos or a double- blind to compare your experimental group to it and also so you know you don't have a bias or anything in the study.
(a) The work done by the force applied by the tractor is 79,968.47 J.
(b) The work done by the frictional force on the tractor is 55,977.93 J.
(c) The total work done by all the forces is 23,990.54 J.
<h3>
Work done by the applied force</h3>
The work done by the force applied by the tractor is calculated as follows;
W = Fd cosθ
W = (5000 x 20) x cos(36.9)
W = 79,968.47 J
<h3>Work done by frictional force</h3>
W = Ffd cosθ
W = (3500 x 20) x cos(36.9)
W = 55,977.93 J
<h3>Net work done by all the forces on the tractor</h3>
W(net) = work done by applied force - work done by friction force
W(net) = 79,968.47 J - 55,977.93 J
W(net) = 23,990.54 J
Learn more about work done here: brainly.com/question/25573309
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The solution for this problem is:
r = [(2.90 + 0.0900t²) i - 0.0150t³ j] m/s²
this is for t in seconds and r in meters
v = dr/dt = [0.180t i - 0.0450t² j] m/s²
tan(-36.0º) = -0.0450t² / 0.180t
0.7265 = 0.25t
t = 2.91 s is the velocity vector of the insect
Parallel circuit
Advandages: 1. Every unit that is connected in a parallel circuit gets equal amount of voltage.
2. It becomes easy to connect or disconnect a new element without affecting the working of other elements.
3. If any fault happened to the circuit, then also the current is able to pass through the circuit through different paths.
Disadvantages: 1. It requires the use of lot of wires.
2. We cannot increase or multiply the voltage in a parallel circuit.
3. Parallel connection fails at the time when it is required to pass exactly same amount of current through the units.
series circuit
Advantages: 1. Series circuits do not overheat easily. This makes them very useful in the case of something that might be around a potentially flammable source, like dry plants or cloth.
2. Series circuits are easy to learn and to make. Their simple design is easy to understand, and this means that it’s simple to conduct repairs .
3. we can add more power devices, they have a higher output in terms of voltage .
4. The current that flows in a series circuit has to flow through every component in the circuit. Therefore, all of the components in a series connection carry the same current.
Disadvantages: 1.If one point breaks in the series circuit,the total circuit will break.
2. As the number of components in a circuit increases ,greater will be the circuit resistance.
Answer:
-6112.26 J
Explanation:
The initial kinetic energy, 
is given by
} where m is the mass of a body and 
is the initial velocity
The final kinetic energy, 
is given by
where 
is the final velocity
Change in kinetic energy, 
is given by
Since the skater finally comes to rest, the final velocity is zero. Substituting 0 for and 12.6 m/s for and 77 Kg for m we obtain
From work energy theorem, work done by a force is equal to the change in kinetic energy hence for this case work done equals <u>-6112.26 J</u>
