You get 493.41 when
you subtract 15.54 from 508.953 using the rules for significant figures.
For addition
and subtraction, look at the decimal portion (i.e., to the right of the decimal
point) of the numbers ONLY. Here is what to do:
1) Count the
number of significant figures in the decimal portion of each number in the
problem. (The digits to the left of the decimal place are not used to determine
the number of decimal places in the final answer.)
2) Add or
subtract in the normal fashion.
3) Round the
answer to the LEAST number of places in the decimal portion of any number in
the problem.
The correct answer between all the choices given is the
third choice or letter C. I am hoping that this answer has satisfied your query
and it will be able to help you in your endeavor, and if you would like, feel
free to ask another question.
Is there any possible chance that at some point in your science
studies, sometime before you were given this question for your
homework, that maybe you might have encountered this formula
for the period of a simple pendulum ?
Period = (2 pi) √(length/gravity) .
If the length is 0.23 meter, and the
acceleration of gravity is 9.8 m/s²,
then the period is
= (2 pi) √(0.23/9.8)
= 0.963... second (rounded)
That's how long it takes for a simple pendulum, 23cm long,
hanging on a massless string and not swinging too far to
the side, to complete one full swing left and right.
Now, if you can figure out how many periods of 0.963 second
there are in 30 seconds, you'll have your answer. I'll leave
that part of it to you.
A: Some physical properties change, but the substance keeps its identity.
Answer:
M g H / 2 = M g L / 2 initial potential energy of rod
I ω^2 / 2 = 1/3 M L^2 * ω^2 / 2 kinetic energy attained by rod
M g L / 2 = 1/3 M L^2 * ω^2 / 2
g = 3 L ω^2
ω = (g / (3 L))^1/2
My calculations state, not rounding, the mass is 1.8
