Answer:
The beach ball's velocity at the moment it was tossed into the air is <u>4.9 m/s.</u>
Explanation:
Given:
Time taken by the ball to reach maximum height is, 
We know that, velocity of an object at the highest point is always zero. So, final velocity of the ball is, 
Also, acceleration acting on the ball is always due to gravity. So, acceleration of the ball is, 
The negative sign is used as acceleration is a vector and it acts in the downward direction.
Now, we have the equation of motion relating initial velocity, final velocity, acceleration and time given as:
Where, 'u' is the initial velocity.
Plug in the given values and solve for 'u'. This gives,
Therefore, the beach ball's velocity at the moment it was tossed into the air is 4.9 m/s
Answer:
w = √[g /L (½ r²/L2 + 2/3 ) ]
When the mass of the cylinder changes if its external dimensions do not change the angular velocity DOES NOT CHANGE
Explanation:
We can simulate this system as a physical pendulum, which is a pendulum with a distributed mass, in this case the angular velocity is
w² = mg d / I
In this case, the distance d to the pivot point of half the length (L) of the cylinder, which we consider long and narrow
d = L / 2
The moment of inertia of a cylinder with respect to an axis at the end we can use the parallel axes theorem, it is approximately equal to that of a long bar plus the moment of inertia of the center of mass of the cylinder, this is tabulated
I = ¼ m r2 + ⅓ m L2
I = m (¼ r2 + ⅓ L2)
now let's use the concept of density to calculate the mass of the system
ρ = m / V
m = ρ V
the volume of a cylinder is
V = π r² L
m = ρ π r² L
let's substitute
w² = m g (L / 2) / m (¼ r² + ⅓ L²)
w² = g L / (½ r² + 2/3 L²)
L >> r
w = √[g /L (½ r²/L2 + 2/3 ) ]
When the mass of the cylinder changes if its external dimensions do not change the angular velocity DOES NOT CHANGE
The forces of gravity between two objects are smaller when the objects are farther apart.
(D) The gravitational force between the astronaut and the asteroid.
Reason :
All the other forces given in the options, except (D), doesn't account for the motion of the astronaut. They are the forces that act between nucleons or atoms and neither of them accounts for an objects motion.
The answer is B (The second one). I'm not sure though.
