Answer: -0.84 rad/sec (clockwise)
Explanation:
Assuming no external torques act on the system (man + turntable), total angular momentum must be conserved:
L1 = L2
L1 = It ω + mm. v . r = 81.0 kg . m2 .21 rad/s – 56.0 kg. 3.1m/s . 3.1 m
L1 = -521.15 kg.m2/sec (1)
(Considering to the man as a particle that is moving opposite to the rotation of the turntable, so the sign is negative).
Once at rest, the runner is only a point mass with a given rotational inertia respect from the axis of rotation, that can be expressed as follows:
Im = m. r2 = 56.0 kg. (3.1m)2 = 538.16 kg.m2
The total angular momentum, once the runner has come to an stop, can be written as follows:
L2= (It + Im) ωf = -521.15 kg.m2/sec
L2= (81.0 kg.m2 + 538.16 kg.m2) ωf = -521.15 kg.m2/sec
Solving for ωf, we get:
ωf = -0.84 rad/sec (clockwise)
Let's call
the mass of the star and
the mass of the planet, which should cancel. The gravitational force should equal the centripetal force:
We compute
This is Keppler's Law. We convert to MKS as we plug in and get
kg
which is about two and a half solar masses if I haven't made any errors.
The law of conservation tells us that no mass is lost. This is true because when wood burns or turns into ash, some of it is escaped as gases like carbon dioxide and water vapor into air . If we calculate the mass of these atmospheric gases that evolved when the wood turned into ash, we would find that the total mass of all these substances including the ash is equal to the log of wood.
Answer:
specific heat
Explanation:
Specific heat is the amount of heat required to change the temperature of 1 gram of a substance by 1°C, and it is related to the chemical composition of the substance