Physics problems...?

Question

Could you please help me with the following questions: I have labelled the questions 1, 2, 3 etc so it's easier..I am not trying to get you to do homework.

Question 1:
How many significant figures are in the following numbers?
a) i) 0.1030
ii) 312.05

b) Using scientific notation, write the following numbers to three significant figures
i) 1026
ii) 0.04555

Question 2:
Alice was working late. When she left work to catch the 6:30 train she found she was nearly 20 minutes late. Thinking back she remembered that she had looked at the clock in the mirror, and seen the time as 5:50. Why was she 20 minutes late for her train?

Question 3:
Use your graphic calculators to evaluate the following. (Express final answers correct to three significant figures.)
a) e= 27.64*(6.38*10^ -2)^2 / (2.48*10^ -4)^2 * 1.07*10^3

Note: * symbol is the multiply sign, / is divide by (the numbers before the / are the numerator and after / is the denominator.

^ symbol is the power of and some are to a negative power ^-2 for example.

Question (cont)
b) f=(5.074*10^ -5)+(8.76*10^- 6)-
(4.17*10^ -5)

Note: Question part b is meant to be all on the one line...it's NOT a fraction

c) g= 1.55sin37.5° / sin29.3°

Note: part c is a fraction..1.55sin37.5° is the numerator and sin 29.3°, denominator (divide by is / sign).

Thankyou so much for helping me.

With the question about the clock..I understand it..I thought it was a digital clock and I kept trying to work out why she would have been late. Then I finally realised it must have been the clock with the hour and minute hands. I understand.

Answer 1

Okay Katie M here we go

1. See reference below
(a)
(i) 3 significant figures (SF)
(ii) 5 SF

(b).
(i) 1.026 e+3 (e+3=10 raised to the third power) [e stands for Exp on your calculator]
(ii) 4.555 e-2 or 45.55 e-3

2. Mirror flips image left to right or right to left
it was 6:10 while she saw 5:50 hence 20 min difference. (I'm glad you got it even before I put it down)

3. Sorry I do not have a graphic calculator :-)
e=27.64*(6.38*10^ -2)^2 / (2.48*10^ -4)^2 * 1.07*10^3=
e=1 957 310 888.9177939646201873048907 (I hope it's right?)
rounding to 3 SF we have
e=1.96 e+9

Continued

b) f=(5.074*10^ -5)+(8.76*10^- 6)-
(4.17*10^ -5)

f=0.000018 1
f=1.81e-5 (shifted 5 decimal places to the right)

c) g= 1.55sin37.5° / sin29.3°

g=1.9281039023601269808335704548322
g=1.93 final answer

Answer 2

1ai: 4 (the final 0 is a sig. fig.)
1aii: 5
1bi: 1.03*10^3
1bii: 4.56*10^-2

2. Others have answered this. 6:10 looks like 5:50 in a mirror.

3a: 1.96*10^9 (more precisely, 1.957311*10^9)
3b: 0.0000178 (the exact answer)
3c: 1.93 (more precisely, 1.928104)

You can check the question 3 results on the online calculator below. Just type in the expressions to the right of the equals sign in 3a and 3b (but delete the spaces between "^" and "-"). Or just copy these:
27.64*(6.38*10^-2)^2 / (2.48*10^-4)^2 * 1.07*10^3
(5.074*10^-5) + (8.76*10^-6) - (4.17*10^-5)
For 3c, you would have to enter the problem as
1.55*sin(37.5*3.1415926/180) / sin(29.3*3.1415926/180)
since the sine function requires the angle to be expressed in radians. The calculator will also accept
1.55*sin(37.5*PI/180) / sin(29.3*PI/180)

Answer 3

1
(a) (i) 4
5
(b) 1.026 x 10^3
4.555 x 10^-2
2/ the image formed by a mirror is leterally inverted. She has seen 5.50 but it was 6.10 actually, the minute hand on 2 rather tha 10. the hour hand moved slightly just after 6

3
1.71 x 10^ -25

Answer 4

the galaxies rotate at speeds inconsistent with their apparent mass is because we do see all of it. I am referring to it as being the theoretical Dark Matter. There are very strong proofs that indicates that dark matter exist. One the is the inconsistent speed of and apparent mass. dark matter makes up about 75% to 80% of the matter in the Universe...

Answer 5

Looks like homework to me! He stated as he smiles and chuckles into the night!

Answer 6

Of course not.
You just dreamt them up.