samistumbo
New member
- Joined
- Aug 17, 2011
- Messages
- 23
Again, I'm sure this doesn't go here but it's a problem I got in my Calculus class, so I'm posting it here.
I have the following question:
If a ball is thrown in the air with a velocity 34 ft/s, its height in feet t seconds later is given by y = 34t − 16t2.
(a) Find the average velocity for the time period beginning when t = 2 and lasting
With the following answers:
(i) 0.5 second.
38 ft/s
(ii) 0.1 second.
31.6 ft/s
(iii) 0.05 second.
30.8 ft/s
(iv) 0.01 second.
30.16 ft/s
(b) Estimate the instantaneous velocity when t = 2.
30 ft
But they're all wrong. Here's how I worked it out:
Avg Velocity= (change in)y/(change in) x= y (2+ h)- y (2)/(2+h) - 2
Then, I worked all that through and got = -16h -30
I plugged the value of h in each time.
AV= -16 (.5)-30= -38ft/sec
AV= -16 (.1) - 30= 31.6 ft/sec
etc, etc.
Can negative numbers work with this? Do I need to just change the signs? Or did I screw up bad somewhere in the math? Also, is there an easier way to figure this out?
I can only submit this one more time, so I need to make SURE I have the right answer this time.
I have the following question:
If a ball is thrown in the air with a velocity 34 ft/s, its height in feet t seconds later is given by y = 34t − 16t2.
(a) Find the average velocity for the time period beginning when t = 2 and lasting
With the following answers:
(i) 0.5 second.
38 ft/s
(ii) 0.1 second.
31.6 ft/s
(iii) 0.05 second.
30.8 ft/s
(iv) 0.01 second.
30.16 ft/s
(b) Estimate the instantaneous velocity when t = 2.
30 ft
But they're all wrong. Here's how I worked it out:
Avg Velocity= (change in)y/(change in) x= y (2+ h)- y (2)/(2+h) - 2
Then, I worked all that through and got = -16h -30
I plugged the value of h in each time.
AV= -16 (.5)-30= -38ft/sec
AV= -16 (.1) - 30= 31.6 ft/sec
etc, etc.
Can negative numbers work with this? Do I need to just change the signs? Or did I screw up bad somewhere in the math? Also, is there an easier way to figure this out?
I can only submit this one more time, so I need to make SURE I have the right answer this time.