FALSE this is not true
(according to Apex 5.3.2 quiz in Physical Science A)
Answer:
There are finally 4 rotations per second.
Explanation:
If a trapeze artist rotates once each second while sailing through the air, and contracts to reduce her rotational inertia to one fourth of what it was. We need to find the final angular velocity. It is a case of conservation of angular momentum such that :

Let
,
and 
So,



So, there are finally 4 rotations per second. Hence, this is the required solution.
Answer:
0.0195 m
Explanation:
= density of hockey puck = 9.45 gcm⁻³ = 9450 kgm³
= diameter of hockey puck = 13 cm = 0.13 m
= height of hockey puck = 2.8 cm = 0.028 m
= density of mercury = 13.6 gcm⁻³ = 13600 kgm³
= depth of puck below surface of mercury
According to Archimedes principle, the weight of puck is balanced by the weight of mercury displaced by puck
Weight of mercury displaced = Weight of puck

Detailed Explanation:
1) Rusting of Iron
4Fe + 3O2 + 2H2O -> 2Fe2O32H2O
Reactants :-
Fe = 4
O = 3 * 2 + 2 = 8
H = 2 * 2 = 4
Products :-
Fe = 2 * 2 = 4
O = 2 * 3 + 2 = 8
H = 2 * 2 = 4
2) Fermentation of sucrose…
C12H22O11 + H2O -> 4C2H5OH + 4CO2
Reactants :-
C = 12
H = 22 + 2 = 24
O = 11 + 1 = 12
Products :-
C = 4 * 2 + 4 = 12
H = 4 * 5 + 4 = 24
O = 4 * 2 + 4 = 12
Looking closely at the way I have taken the total number of elements on the reactants and products side, you can solve the rest.
All the Best!
Answer:
Explanation:
Displacement can be displayed as a vector, this because it has magnitud and direction. Because of this, we can think John's Resultant Displacement as the join of this two vectors.
The First Vector is from the 249 Km Marker to the 141 Km Marker, which give us a Vector with a Magnitude equals to 108 Km.
The Second Vector goes from 141 Km Marker to the 174 Km Marker, which give us a Vector with a Magnitude equals to 33 Km.
However is important to know the direction for each Vector, we notice that John was traveling on one direction and then he returned. This makes our Vector to have a different direction, and this means difference signs. Difference signs means substraction. So, the Third Vector will be:
Third Vector = 108 Km - 33 Km
Third Vector = 75 Km