Question

very difficult the ans found here wrong

A sprinter runs a 100 m dash in 12.0 s. She starts from rest

with a constant acceleration ax for 3.0 s and then runs with constant

speed for the remainder of the race. What is the value of ax?


0 0
Add a comment Improve this question Transcribed image text
Answer #1

ax=3.2m/s2

answered by: Kelsie Johnson
Add a comment
Answer #2

SOLUTION :


!00m completed in 12 sec.


Initial speed = 0 m/s

Run for 3 sec at constant acceleration ax and then runs at constant speed.


Speed after 3 sec = ax * 3  = 3 ax m/s


Average speed during first 3 sec of acceleration = (3 ax + 0)/2 = 1.5 ax m/s 


So, we can consider run of 3 sec. at average speed of 1.5  ax m/s and remaining 9 sec at the speed of 9 sec.


So, 


Distance run in 12 sec = 1.5 ax * 3 + 3.0 ax * 9 

=> 100 = 4.5 ax + 27 ax

=> 100 = 31.5 ax 

=> ax = 100/31.5

=> ax = 3.1746 m/s^2 = 3.175 m/s^2 approx. (ANSWER).

answered by: Tulsiram Garg

> In the 6th line, correct, " remaining 9 sec at the speed of 9 sec. " as " remaining 9 sec at the speed of 3 ax m/s " .

Tulsiram Garg Tue, Dec 14, 2021 8:03 AM

Add a comment
Know the answer?
Add Answer to:
very difficult the ans found here wrong
Your Answer:

Post as a guest

Your Name:

What's your source?

Earn Coins

Coins can be redeemed for fabulous gifts.

Not the answer you're looking for? Ask your own homework help question. Our experts will answer your question WITHIN MINUTES for Free.
Similar Homework Help Questions
ADVERTISEMENT
Free Homework Help App
Download From Google Play
Scan Your Homework
to Get Instant Free Answers
Need Online Homework Help?
Ask a Question
Get Answers For Free
Most questions answered within 3 hours.
ADVERTISEMENT
ADVERTISEMENT
ADVERTISEMENT