In which situation is the acceleration of the car negative?
a.)the velocity of a car was 75 km/h
b.)the velocity of a car reduced from 50 km/h over one minute
c.)the velocity of a car increased from 40 km/h to 75km/h over 15 minutes
d.)the velocity of a car increased from 40 km/sh at 2: 00pm and at 4: 00pm the velocity of the car was 85 km/h

B) The velocity of the car reduced from 50k/m over one min.

Answer is: B.)The velocity of a car reduced from 50 km/h over one minute.

Ending velocity is defined as the velocity attained by a body after completing distance at certain time interval:

v(ending velocity) = v(initial velocity) + a·t.

a is acceleration attained by the body (in this examle car).

t is time (in this example one minute).

Because velocity is reduced, acceleration has negative sign.

An car average acceleration over a period of time is its change in velocity.

i believe it is-

d.) gravity pulled particles of dust and gas together to form planets.