Explanation:
When a constant force acts upon an object the acceleration of the object varies inversely with its mass.

or

If m₁ = 21 kg, a₁ = 3 m/s², m₂ = 9 kg
We need to find a₂
So,

So, if mass is 9 kg, its acceleration is 7 m/s².
When the reactants are heated, the average kinetic energy of the molecules increases. This means that more molecules are moving faster and hitting each other with more energy. If more molecules hit each other with enough energy to react, then the rate of the reaction increases.
Answer:
<em>Second option</em>
Explanation:
<u>Linear Momentum</u>
The linear momentum of an object of mass m and speed v is
P=mv
If two or more objects are interacting in the same axis, the total momentum is

Where the speeds must be signed according to a fixed reference
The images show a cart of mass 2m moves to the left with speed v since our reference is positive to the right

The second cart of mass m goes to the right at a speed v

The total momentum before the impact is

The total momentum after the collision is negative, both carts will join and go to the left side
The first option shows both carts with the same momentum before the collision and therefore, zero momentum after. It's not correct as we have already proven
The third option shows the 2m cart has a positive greater momentum than the other one. We have proven the 2m car has negative momentum. This option is not correct either
The fourth option shows the two carts keep separated after the collision, which contradicts the condition of the question regarding "they hook together".
The second option is the correct one because the mass
has a negative momentum and then the sum of both masses keeps being negative
To solve this problem we will apply the concepts related to centripetal acceleration, which will be the same - by balance - to the force of gravity on the body. To find this acceleration we must first find the orbital velocity through the Doppler formulas for the given periodic signals. In this way:

Here,
Orbital Velocity
Maximal Wavelength
Average Wavelength
c = Speed of light
Replacing with our values we have that,

<em>Note that the average signal is 3.000000m</em>

Now using the definition about centripetal acceleration we have,

Here,
v = Orbit Velocity
r = Radius of Orbit
Replacing with our values,



Applying Newton's equation for acceleration due to gravity,

Here,
G = Universal gravitational constant
M = Mass of the planet
r = Orbit
The acceleration due to gravity is the same as the previous centripetal acceleration by equilibrium, then rearranging to find the mass we have,



Therefore the mass of the planet is 