In a controlled scientific experiment, a scientist A. alters one test variable (independent variable) and observes the effects on other test variables (independent variables). B. alters one outcome variable (dependent variable) and observes the effects on other outcome variable (dependent variables). C. alters the test variable (independent variable) and observes the effects on the outcome variable (dependent variable).

C )

Explanation:

Controlled scientific experiment tests scientific assumption (hypothesis), under controlled conditions.

In controlled scientific experiment, alters the test variable (independent variable) and observes the effects on the outcome variable (dependent variable).

Eg : Studying impact of sunlight on plant's group, where former independent variable is altered & its effects on dependent outcome variable is observed.

(newtons first law)

conservation of momentum law states :

momentum before collision = momentum after collision

momentum p (kg-m/s)= mass * velocity

say moving car=1 000 kg, velocity = 10 m/s then p = 1 000*10= 10 000 kg-m/s

say still car = 2 000 kg, velocity = 0 m/s then p = 2 000* 0 = 0 kg-m/s

total momentum prior to collision = 10 000 + 0 = 10 000 kg-m/s

momentum after collision = 10 000 kg-m/s

mass now = 1 000 kg+2 000 kg = 3 000 kg

10 000 = 3 000 kg* velocity m/s

10 000/3 000 = velocity

3.33 m/s = velocity after collision

an impulse is a force applied over time , momentum is exclusive of external forces and a perfect collision is implied