Answer:
gravity effects only the mass of an object
Explanation:
an acorn is heavier that a stick and it's round shape gives it less wind resistance so gravity pulls it down faster. A stick vertical has little wind resistance but when rotated to when it is horizontal it has more resistance so it slows down but the the force of gravity is still as strong. A leaf has very little mass and it's shape provideds lots of wind resistance so it falls slower. The moon is not only effected by the earth's gravity it is also effected by the suns. It has its own gravity as well. with all these factors it stays in place and moves with the earth.
Answer:
Part(a): The final angular velocity is
Part(b): The ratio of the rotational energies is ,showing the the energy of th system will decrease.
Explanation:
Part(a):
If '' be the moment of inertia of an object and '' be its angular velocity then the angular momentum '' of the object can be written as
If '' and '' be the moment of inertia of the two cylinders and '' and '' be the initial angular velocity of the cylinders and '' and '' be their respective final angular velocity, then from conservation of angular momentum,
Given, . From the above expression
Part(b):
Initial kinetic energy
and Final kinetic energy
Substituting the value of ,
The above expression shows that the ebergy of the system will decrease.
The speed after 21 s is 18.9 m/s and the total time required for the train to reach a speed of 34 m/s is 14.4 s
<h3>
What is Speed ?</h3>
Speed is a distance travelled by a body per time taken. It is a scalar quantity and it is measured in m/s
Given that at Initially stationary, a train has a constant acceleration of 0.9 m/s2.
(a) What is its speed after 21 s?
- Acceleration a = 0.9 m/s²
Using v = u + at
Substitute all the parameters into the equation
v = 0 + 0.9 x 21
v = 18.9 m/s
(b) What is the total time required for the train to reach a speed of 34 m/s?
Let first calculate for total distance by using
v² = u² + 2as
34² = 18.9² + 2 × 0.9 × S
1156 = 357.21 + 1.8S
1.8S = 1156 - 357.21
1.8S = 798.79
S = 798.79 / 1.8
S = 443.8 m/s
v = u + at
34 = 21 + 0.9t
0.9t = 34 - 21
0.9t = 13
t = 13/0.9
t = 14.44s
Therefore, its speed after 21 s is 18.9 m/s and the total time required for the train to reach a speed of 34 m/s is 14.4 s
Learn more about Speed here: brainly.com/question/24739297
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