To calculate the number of sig figs
1. Count ALL nonzero numbers
2. If the zero is between 2 numbers, count it
3. If in a decimal the zero is at the end, count it
4. In a decimal all the zeros before the first nonzero number are placeholders and don't count them
5. In a number greater than zero all zeros AFTER the last nonzero number are placeholders and don't count them.
A - 5
B - 2
C - 3
D - 1
E - 4
No the density does not change. Density is a ratio D=m/v no matter how much of a substance you have its mass will be proportional.
When doing density labs sometimes you might get different answers due to errors that are unavoidable.
Answer: 87500J
Explanation:
Given that,
Power exerted by crane = 3,500 W
Time taken = 25 seconds
work done by crane = ?
Since power is the rate of work done per unit time, then power is workdone by the crane divided by the time taken.
i.e power = work / time
3,500 W = work / 25 seconds
Work = 3500W x 25 seconds
Work = 87500J
Thus, 87500 joules of work was done by the crane.
Energy = mc (delta T) where m is the mass in kg, c is the specific heat capacity, and delta T is the change in temperature.
450 = (45x10^-3)c (78-22)
450 = (0.045)c (56)
c = 178.57 J/kgK
