Yes, because gravity will pull objects down to Earth.
The Celsius scale (

).
In the Celsius temperature scale, the temperature at which water freezes is set conventionally at

, while the temperature at which the water boils is set at

. The Celsius degree is then defined as the unit corresponding to 1/100 of this time interval, between the temperature of freezing and boiling of the water.
Answer:
1.029
Explanation:
1.0090 can also be looked at as "1.009"
0.02 can also be looked at as "0.020"
I think of it as 20+9 which is 29. There for your answer should be 1.029. There are no measurement rules applying to this equation since they are both in centimeters. So you don't have to convert anything.
Suppose car A is moving with a velocity Va, and car b with a velocity Vb,
According the principle of conservation of momentum:
Va x Ma + Vb x Mb = (Ma + Mb) V
V = (Va x Ma + Vb x Mb)/(Ma +Mb)
V = speed of cars after coupling
V = (Va x 20 mg + Vb x 15 mg)/(20 mg + 15 mg)
Put in the values of Va and Vb, and get the V