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SSSSS [86.1K]
3 years ago
13

For the following questions, imagine the book drops in free fall and falls a distance d. For the system of the book and earth, t

he change in total energy of the system if the book falls a distance d _______.(A) is positive.(B) is negative.(C) is zero.(D) has a sign which cannot be determined.
Physics
1 answer:
alukav5142 [94]3 years ago
8 0

Answer:

C) is zero

Explanation:

According to the law of energy conservation, the total mechanical energy of the object is conserved. A book falling a distance d would have a change in potential energy, resulting in the same change in kinetic energy. But the total mechanical energy must be the same. So there's 0 change in total energy of the system.

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An 85,000 kg stunt plane performs a loop-the-loop, flying in a 260-m-diameter vertical circle. at the point where the plane is f
konstantin123 [22]
A) When the plane is flying straight down, there are three forces acting on it:
- the centripetal force  F=m \frac{v^2}{r}, directed toward the center of the circle (so, horizontally)
- the weight of the plane: W=mg, downward, so vertically
- a third force, given by the propulsion of the plane, which is accelerating it towards the ground (because the problem says that the plane has an acceleration of a=12 m/s^2 towards the ground)

The radius of the circle is r= \frac{260 m}{2} = 130 m, so the centripetal force acting on the plane is
F_c=m \frac{v^2}{r} = \frac{(85000 kg)(55 m/s)^2}{130 m}=1.98 \cdot 10^6 N
On the vertical axis, we have two forces: the weight
W=mg=(85000 kg)(9.81 m/s^2)=8.34 \cdot 10^5 N
and the other force F given by the propulsion. Since we know that their sum should generate an acceleration equal to a=12 m/s^2, we can find the magnitude of this other force F by using Newton's second law:
F+mg=ma
F=m(a-g)=(85000kg)(12 m/s^2-9.81 m/s^2)=1.86 \cdot 10^5 N

So, the net force acting on the plane will be the resultant of the centripetal force (acting in the horizontal direction) and the two forces W and F (acting in the vertical direction):
R= \sqrt{(F_c^2+(W+F)^2}=
= \sqrt{(1.98\cdot 10^6N)^2+(8.34 \cdot 10^5N+1.86 \cdot 10^5 N)^2}  =2.23 \cdot 10^6 N

(b) The tangent of the angle with respect to the horizontal is the ratio between the sum of the forces in the vertical direction (taken with negative sign, since they are directed downward) and the forces acting in the horizontal direction, so:
\tan \theta =  \frac{-(W+F)}{F_c}= -0.5
And so, the angle is
\theta = \arctan (-0.5)=-26.8 ^{\circ}
 
7 0
3 years ago
Infer why the output force exerted by a rake must be less than input force?
adell [148]
<h3><u>Answer and Explanation</u>;</h3>
  • input force refers to the force exerted on a machine, also known as the effort, while the output force is the force machines produce or the Load. The ratio of output force to input force gives the mechanical advantage of a simple machine
  • <em><u>The output force exerted by the rake must be less than the input force because one has to use force while raking. The force used to move the rake is the input force. </u></em>
  • <em><u>The rake is not going to be able to convert all of the input force into output force, the force the rake applies to move the leaves, because of friction.</u></em>
5 0
3 years ago
Which of the following is most closely related to the specific heat of a substance?A. its temperatureB. its melting pointC. its
swat32

Answer:

option (C)

Explanation:

The amount of heat required to raise the temperature of substance of unit mass by unit degree is called specific heat of that substance.

Its SI unit is Joule / Kg °C.

Every material has a constant value of specific heat.

So, option (c) is correct.

4 0
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The purpose of _______'s ministry was to bring the nation in exile back to the God of their covenant
Anit [1.1K]
The answer would be Jeremiah
6 0
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Which is a FALSE statement about elements?
rodikova [14]

C is incorrect because the atomic number and symbol are the only ones displayed.

I think it could be A but it is most likely C

Hope it helps!!

3 0
3 years ago
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