Write a hypothesis about how the number of half-lives affects the number of radioactive atoms. Use the "if . . . then . . . beca
2 answers:
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During the phase transition vapour --> liquid water, the temperature of the water does not change; the molecules of water release heat and the amounf of heat released is equal to
where
m is the mass of the water
is the latent heat of evaporation.
For water, the latent heat of evaporation is
, while the mass of the water is
so, the amount of heat released in the process is
where
m is the mass of the water
For water, the latent heat of evaporation is
so, the amount of heat released in the process is
Answer:
acceleration 8 km/h/s south
Explanation:
First of all, let's remind that a vector quantity is a quantity which has both a magnitude and a direction.
Based on this definition, we can already rule out the following two choices:
distance: 40 km
speed: 40 km/h
Since they only have magnitude, they are not vectors.
Then, the following option:
velocity: 5 km/h north
is wrong, because the car is moving south, not north.
So, the correct choice is
acceleration 8 km/h/s south
In fact, the acceleration can be calculated as
where
v = 40 km/h is the final velocity
u = 0 is the initial velocity
t = 5 s is the time
Substituting,
And since the sign is positive, the direction is the same as the velocity (south).
Momentum is conserved if and only if sum of all forces which are exserted on system equals zero. In our situation there are only internal forces, so by Newton's third law their vector sum is 0.
So .
Kinetic energy of system at first: . After:
. The secret is that other energy is in work of deformation forces (they in turn heat a bullet and a block).
Answer is A)