When the object is big enough to contract itself into a ball.
Observations and Data are FACTS. Scientists use observations and data to draw a conclusion. Observations lead to the recording of data. Scientists ask questions about their observations and then collect data to answer their questions, then they have their evidence. Opinions are not facts, they are simply beliefs or value judgements. Then the scientist should repeat the experiment the results from different scientists should be similar- if the results are not similar and consistent then the experiment must be done again.
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Answer:
0.99Hz
Explanation:
Using F= -mx ( spring force)
At equilibrium the gravitational force will be balanced by the spring force so mg= kx
K= mg/ 0.25 N/m
But
Frequency f= 1/2pi √g/0.25
Frequency is 0.99Hz
A 13-kg sled is moving at a speed of 3.0 m/s. At which of the following speed will the sled have twice as much kinetic energy?
4.2 m/s
Answer:
Rise in level of fluid is 0.11 m
Rise in level of fluid in case of mercury is 0.728 cm or 7.28 mm
Solution:
As per the question:
Density of oil, 
Change in Pressure in the tank, 
Density of the mercury, 
Now,
To calculate the rise in the level of fluid inside the manometer:
We know that:
1 mmHg = 133.332 Pa
Thus

Also,

where
g = acceleration due to gravity
h = height of the fluid level

h = 0.11 m
Now, if mercury is used:


h = 0.00728 m = 7.28 mm