Answer:
Gravity
Explanation:
Thats the answer bucko. Gives the brainliest or I die
Answer:
Explanation:
Given
Each student exert a force of 
Let mass of car be m
there are 18 students who lifts the car
Total force by 18 students 
therefore weight of car 
mass of car 

(b)
Answer:
Two scientists in a lab examining vials of urine they are analyzing for levels of excreted protein.
Explanation:
Answer:
Suppose two objects of different masses are moving with different velocities in the same direction on a straght-line before collision. After collision, they stick together and move with common (the same) velocity