2. Describe two ways to change the
frictional force between two solids surfaces.
Change the lubrication between the two surfaces
Change the normal force between the two surfaces
3. How does air resistance affect the
velocity of a falling object?
4. What two sources of friction do you
have to overcome when you are walking?
5. If you push a chair across the floor
at a constant velocity, how does the force of friction compare with the force
exert? Explain.
6. If you push a book against a wall
hard enough, it will not slide down even though gravity is pulling it. Use what
you know about Newton’s laws of motion to explain why the book doesn’t fall.
B.This is true because weight is the amount of matter in an object. Because gravity is a force, and force is proportional to weight, both gravity and weight vary in different places in the universe.
C. This is true because gravitational force is the magnitude of weight acting on an object and since weight varies in different places in the universe, gravitational force also varies.
D. This is true because weight is the magnitude of gravitational force acting on an object, and since gravitational force varies in different places in the universe, weight also varies.
Explanation :
We know that the weight of an object is given by :
Where,
m is the mass
g is the acceleration due to gravity.
The value of g changes from one location to another.
An object's weight is dependent upon its location in the universe. This statement is true. This is because g varies in different places so the weight also varies.
Hence, the correct option is (D) " This is true because weight is the magnitude of gravitational force acting on an object, and since gravitational force varies in different places in the universe, weight also varies ".
The theory of evolution is that organisms evolve over time.
1) Final angular velocity is 5.22 rad/s
2) Change in kinetic energy: 639.8 J
Explanation:
1)
In absence of external forces, the angular momentum of the merry-go-round must be conserved.
So we can write:
where
is the initial moment of inertia
is the final moment of inertia
is the initial angular velocity
is the final angular velocity
At the beginning, we have:
The moment of inertia is the sum of the moment of inertia of the cylinder + the moment of inertia of the man, therefore:
The man later walks to a point 1 m from the centre, so the final moment of inertia is:
Therefore, the final angular velocity is
2)
The angular velocity of the merry-go-round rotating is given by
In the first situation, we have
Therefore
In the second situation, we have
Therefore
So the change in kinetic energy is
Learn more about circular motion:
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