1) C. velocity
Acceleration is defined as the rate of change of velocity per unit time. In formulas:

where
is the change in velocity
is the time interval
Therefore, the correct answer is C. velocity.
2) A. 9.8m/s/s
Earth's gravity is a force, so it produces an acceleration on every object with mass located on the Earth's surface. This acceleration can be calculated, as it is given by the formula

where
is the gravitational constant
is the Earth's mass
is the Earth's radius
By substituting these numbers into the formula, one can find that the acceleration due to Earth's gravity is
.
A. 1/9
Explanation:
The gravitational force between two objects is given by

where
G is the gravitational constant
m1 and m2 are the two masses
r is the distance between the two masses
From the formula, we see that the magnitude of the force is inversely proportional to the square of the distance: therefore, if the distance is tripled (increased by a factor 3), the magnitude of the force changes by a factor

The right answer for the question that is being asked and shown above is that: "1-4-3-2." (main sequence-->red giant-->supergiant-->white dwarf). Assume that all four H-R diagrams below represent a star in different stages of its life, after it starts to fuse hydrogen in its core.
Acceleration = (change in speed) / (time for the change.
change in speed = (ending speed) - (starting speed) = 9 m/s.
Acceleration = (9 m/s) / (period of 1) .
We don't know the units of the 'period of 1'.
If it means '1 second', then the acceleration is 9 m/s² .
Applying the ideal gas equation:
PV = nRT
PV = (mass/Mr)RT
mass = PVMr/RT
mass = (101325 x 4672.2 x 4) / (8.314 x 297)
= 766887.3 kg
= 7.7 x 10⁵ kg