Question 4
B. Toby is correct because the rock is experiencing a negative acceleration, causing its positive velocity to decrease until the rock reaches a velocity of O m/s before becoming negative.
Question 5
At the maximum height, velocity is 0, so:
v = v₀ - gt
0 = 14.75 - 9.8t
t = 14.75/9.8
t = 1.5 s (OPTION A)
Answer:
a) The x coordinate of the third mass is -1.562 meters.
b) The y coordinate of the third mass is -0.944 meters.
Explanation:
The center of mass of a system of particles (
), measured in meters, is defined by this weighted average:
(1)
Where:
- Mass of the i-th particle, measured in kilograms.
- Location of the i-th particle with respect to origin, measured in meters.
If we know that
,
,
,
,
and
, then the coordinates of the third particle are:
![(-0.500\,m, -0.700\,m) = \frac{(1\,kg)\cdot (-1.20\,m,0.500\,m)+(4.50\,kg)\cdot (0.600\,m,-0.750\,m)+(4\,kg)\cdot \vec r_{3}}{1\,kg+4.50\,kg+4\,kg}](https://tex.z-dn.net/?f=%28-0.500%5C%2Cm%2C%20-0.700%5C%2Cm%29%20%3D%20%5Cfrac%7B%281%5C%2Ckg%29%5Ccdot%20%28-1.20%5C%2Cm%2C0.500%5C%2Cm%29%2B%284.50%5C%2Ckg%29%5Ccdot%20%280.600%5C%2Cm%2C-0.750%5C%2Cm%29%2B%284%5C%2Ckg%29%5Ccdot%20%5Cvec%20r_%7B3%7D%7D%7B1%5C%2Ckg%2B4.50%5C%2Ckg%2B4%5C%2Ckg%7D)
![(-4.75\,kg\cdot m, -6.65\,kg\cdot m) = (-1.20\,kg\cdot m, 0.500\,kg\cdot m) + (2.7\,kg\cdot m, -3.375\,kg\cdot m) +(4\cdot x_{3},4\cdot y_{3})](https://tex.z-dn.net/?f=%28-4.75%5C%2Ckg%5Ccdot%20m%2C%20-6.65%5C%2Ckg%5Ccdot%20m%29%20%3D%20%28-1.20%5C%2Ckg%5Ccdot%20m%2C%200.500%5C%2Ckg%5Ccdot%20m%29%20%2B%20%282.7%5C%2Ckg%5Ccdot%20m%2C%20-3.375%5C%2Ckg%5Ccdot%20m%29%20%2B%284%5Ccdot%20x_%7B3%7D%2C4%5Ccdot%20y_%7B3%7D%29)
![(4\cdot x_{3}, 4\cdot y_{3}) = (-6.25\,kg\cdot m,-3.775\,kg\cdot m)](https://tex.z-dn.net/?f=%284%5Ccdot%20x_%7B3%7D%2C%204%5Ccdot%20y_%7B3%7D%29%20%3D%20%28-6.25%5C%2Ckg%5Ccdot%20m%2C-3.775%5C%2Ckg%5Ccdot%20m%29)
![(x_{3},y_{3}) = (-1.562\,m,-0.944\,m)](https://tex.z-dn.net/?f=%28x_%7B3%7D%2Cy_%7B3%7D%29%20%3D%20%28-1.562%5C%2Cm%2C-0.944%5C%2Cm%29)
a) The x coordinate of the third mass is -1.562 meters.
b) The y coordinate of the third mass is -0.944 meters.
Answer:
Both statements I, and II are true
Explanation:
I)One is true.The number of protons of the element is the defining characteristic of it. This is, if we take a proton or add a proton to a nucleus we will be changing the element. Therefore, the number of protons is the same for all neutral and not neutral atoms of that element.
II)Two is true. If an atom is neutral, it will have the same number of electrons and protons. As the number of protons for an element cannot change (see I), then the number of electrons will be the same for all neutral atoms of this element.
III)Three is false. We can have a neutral atoms of the same element with different number of neutrons, as neutrons do not change the charge of the atom(they change their mass, though). These are called Isotopes.
Answer: A sealed calorimeter is a closed system because thermal energy is not transferred to the environment.
A closed system is an isolated system where there is no transfer of energy with its surroundings. Also the system is not subjected to any external force whose source is external to the system.