Answer:
d) The trampoline pushes back up on the gymnast.
Explanation:
According to Newton's third law of motion; for every action force, there is an equal and opposite reaction force. The action force and reaction force are reciprocal to one another i.e. they act oppositely to one another. The reaction force acts in an opposite direction to the action force and vice versa.
In this question, a gymnast pushed down on a trampoline during a routine. This is called the ACTION FORCE. In conformity to Newton's third law, the trampoline pushes back up on the gymnast. This opposite force is called the REACTION FORCE.
According to the question, the object is placed at 2F
The ray diagram is shown in the figure attached.
According to the figure:
Object AB is at 2F₁
First, we draw a ray parallel to principal axis.
So, it passes through focus after refraction.
We draw another ray which passes through optical center.
So, the ray will go through without any deviation.
Where both refracted rays meet is point A' and the image formed is A'B'
This image is formed at 2F₂
We can say that:
- Image is real.
- Image is inverted.
- Image is exactly the same size as the object.
Derived Units Table: The Table Shows the List of Derived Units
Quantity Formula SI Derived Unit
Force Mass x Acceleration
Work Energy Force x Displacement Power/Time Kg. m.s-2
Pressure, Stress Force/Area Kg.m-1.s-2
Current density J = I/A A.m-2
Explanation:
They probably put "rolls without slipping" in there to indicate that there is no loss in friction; or that the friction is constant throughout the movement of the disk. So it's more of a contingency part of the explanation of the problem.
(Remember how earlier on in Physics lessons, we see "ignore friction" written into problems; it just removes the "What about [ ]?" question for anyone who might ask.)
In this case, you can't ignore friction because the disk wouldn't roll without it.
As far as friction producing a torque... I would say that friction is a result of the torque in this case. And because the point of contact is, presumably, the ground, the friction is tangential to the disk. Meaning the friction is linear and has no angular component.
(You could probably argue that by Newton's 3rd Law there should be some opposing torque, but I think that's outside of the scope of this problem.)
Hopefully this helps clear up the misunderstanding for you.
The amount of energy before and after any energy transformations remain the same because energy cannot be created or destroyed. From the law conservation of energy; any time energy is transferred between two objects, or converted from one form into another, no energy is created and none is destroyed. The total amount of energy involved in the process remains the same.
