During a collision with another car, the occupants of a minivan initially travelling at 4.0 m/s come to a complete stop in 0.5 s. What was the acceleration of the occupants of the minivan? a) 8.0 m/s2

b) –8.0 m/s2

c) 2.0 m/s2

d) –2.0 m/s2

b) - 8.0

Explanation: Acceleration is a vector indicating a rate an object's velocity changes over time:

a =

and its SI unit is

For the minivan to stop, it takes a period of 0.5s:

a =

a = 8.0

As a vector, acceleration has magnitude (8) and direction. Since it is stopping, the minivan has a direction opposite to the other car, which means acceleration is negative. So: a = .

i had this question and the answer was 3.15 miles.

martina travels from school to her mom's office. from there, she walks to school. after school, she walks to the library and then to a friends house before finally ending back at home. find martina's total distance traveled.

a) 0 miles  

b) 0.4 miles  

c) 1 mile  

d) 3.15 miles