A force of 20 N acts toward the east. Another force of 27 N acts at the same point toward the west. What is the magnitude and di
1 answer:
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Answer:
Because the light reflects multiple times until it gets to the Cassegrain focus.
Explanation:
The Cassegrain design can be seen in a reflecting telescope. In this type of design the light is collected by a concave mirror, and then intercepted by a secondary convex mirror, and sends it down to a central opening in the primary mirror (concave mirror), in which a detector is placed (Cassegrain focus)
Since, the light is reflected many times due to Cassegrain design, that leads to shorter telescopes.
Answer:
v = 12.1 m/s
Explanation:
- When at the top of the circle, there are two forces acting on the combined mass of the rider and the motorcycle.
- These are the force of gravity (downward) and the normal force, which is directed from the surface away from it, perpendicular to the surface.
- In this case, as the motorcycle runs in the interior of the circle, at the top point this force is completely vertical, and is also downward.
- Since the motorcycle is moving in a vertical circle, there must be a force, keeping the object moving around a circle.
- This force is the centripetal force, aims towards the center of the circle, and is just the net force aiming in this direction at any point.
- At the top point, this force is just the sum of the normal force and the weight of the mass of the rider and the motorcycle combined, as follows (we take the direction towards the center as positive):
- Now, we know that the centripetal force is related with the tangential speed at this point and the radius of the circle as follows:
- Since the normal force takes any value as needed to make (1) equal to (2), if the speed diminishes, it will be needed less force to keep the equality valid.
- In the limit, when the motorcyvle tires barely touch the surface, this normal force becomes zero.
- In this condition, from (1) and (2), we can find the minimum possible value of the speed that still keeps the motorcycle touching the surface, as follows:
The force of gravity produces acceleration in all C. freely falling objects and this is known as acceleration due to gravity
Explanation:
A body is said to be in free fall when there is only one force acting on the body: the force of gravity.
Gravity is a force that acts downward, i.e. towards the Earth's centre.
If we are near the Earth's surface, the magnitude of the force of gravity on a body is given by
where:
m is the mass of the body
g is known as the acceleration of gravity , whose value near the Earth's surface is ).
We can apply Newton's second law on an object in free-fall, to find its acceleration. In fact, we have:
where F is the force acting on the body and a is its acceleration.
Solving for the acceleration,
And substituting F,
Therefore, every object in free-fall accelerates at towards the ground.
Learn more about free fall here:
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