A ROBOT USED IN A PHARMACY PICKS UP A MEDICINE BOTTLE AT T = 0...

Câu 39. A robot used in a pharmacy picks up a medicine bottle at t = 0. It accelerates

at 0.20 m/s

²

for 5.0 s, then travels without acceleration for 69 s and finally decelerates

at -0.40 m/s

²

for 3.0 s to reach the counter where the pharmacist will take the medicine

from the robot. From how far away did the robot fetch the medicine?

A. 71,7 m. B. 78,4 m. C. 72,7 m. D. 64,7 m.

Hướng dẫn

 

   

0, 2.5 1 /

v v m s

 

B

A

* From figure:

1 1

   

        

2

2



s AB BC CD m

.0, 2.5 1.69 1.3 0, 4 .3 72, 7

2 2

 Choose C.