Well first of all, I think the students may have been correct.
If they didn't use distilled water, and if it wasn't exactly at
standard temperature, then the mass of 25.0 mL could
very well be 25.4 grams. We don't know that there was
any 'error' in their measurement at all.
But the question says there was, so we'll do the math:
The 'error' was (25.4 - 25.0) = +0.4 gram
As a fraction of the 'real' value, the error was
+0.4 / 25.0 = +0.016 .
To change a decimal to a percent, move the
decimal point two places that way ===> .
+ 0.016 = +1.6 % .
Their measurement was 1.6% too high.
Let's not call it an 'error'. Let's just call it a 'discrepancy'
between the measured value and the 'accepted' value. OK ?
Answer: b
Explanation: the two pieces will repel as both have obtained a static charge.
Answer: K.E = 0.4 J
Explanation:
Given that:
M = 1.0 kg
h = 0.04 m
K.E = ?
According to conservative of energy
K.E = P.E
K.E = mgh
K.E = 1 × 9.81 × 0.04
K.E = 0.3924 Joule
The kinetic energy of the pendulum at the lowest point is 0.39 Joule
Answer:
0.11 kg
Explanation:
Ft = MV
Ft = momentum 5.22kg m/s
M = mass
V = velocity 48.3m/s
Therefore
5.22 = M x 48.3
Divide both sides by 48.3
5.22/48.3 = M x 48.3/48.3
0.11 = M
M = 0.11kg
An object that's moving doesn't necessarily change its speed or acceleration. Also, the force applied to it doesn't need to change ... in fact, a moving object doesn't need ANY force applied to it in order to keep moving.
But any moving object WILL have a change in its position ... THAT's how you know it's moving, and that's WHY you say "It's moving !". (choice-B)
