6) If a car goes from 20 miles per hour to 10 miles per hour in 5 seconds, find its acceleration.
a.2 miles per hour per second
b.5 miles per hour per second
c.-2 miles per hour per second
d.10 miles per hour per second

Respuesta :

Answer;

C.-2 miles per hour per second

Explanation;

Acceleration = change in velocity / time

Acceleration = (final velocity - initial velocity )/time  

Acceleration = (v - u)/t  

Given: u = 20 miles per hour, v = 10 miles per hour  

t = 5 seconds  

Acceleration = (10 - 20)/5  

Acceleration = -10/5  

Acceleration = -2 miles per hour per second  


ANSWER IS C

The car is accelerating at -2 miles per hour per second. Although the units seem odd, it is distance/time2, which is acceptable for acceleration. a=

v

t

=10-20/5=-2.