A ball of mass 0.25 kg moving horizontally with a velocity of 13 ms-1 is hit with a bat. The final velocity of the ball is 19 ms-1 in the opposite direction. If the bat is in contact with the ball for 0.02 s, find the average force of the bat on the ball.
-
Finished your HSC? Check out our University Discussion, Non-School forums or help out next year's HSC students! -
YOU can help the next generation of students in the community! Share your trial papers and notes on our Notes & Resources page
help with motion problemz (1 Viewer)
- Thread starter clicker
- Start date
BlackJack
Vertigo!
You are given mass and velocity: try dealing in momentums. The units tells you that total change in momentum is force * time.
DementedDonkey
Member
- Joined
- Jul 2, 2004
- Messages
- 102
- Gender
- Female
- HSC
- 2005
I got -400N, but don't trust that I suck at motion and my half yearly is tomoro.. gahhh
ok what i did (so please correct me anyone who knows where i went wrong)...
into the equation v=u+at i sub'd v=-19, u=13 and t=0.02.. to find a. From this i found that a=-1600ms-2. Then sub'd into F=ma, where m=0.25 and a =-1600, to get F =-400N. the formulas and stuff seem too simple.. I dunno, someone let me know aye?!
ok what i did (so please correct me anyone who knows where i went wrong)...
into the equation v=u+at i sub'd v=-19, u=13 and t=0.02.. to find a. From this i found that a=-1600ms-2. Then sub'd into F=ma, where m=0.25 and a =-1600, to get F =-400N. the formulas and stuff seem too simple.. I dunno, someone let me know aye?!
rama_v
Active Member
I got -400 as well. Dontyou just reverse the vectors (so that means the velocity was 32 m/s left) and then calculate a using (v-u)/t and then sub into f=ma?
DementedDonkey
Member
- Joined
- Jul 2, 2004
- Messages
- 102
- Gender
- Female
- HSC
- 2005
im not sure about the 32ms-1 left thing... say the ball was initially travelling to the right, wouldnt you minus the vectors with the change in direction not add them? (ie, 13-19?).. nah that'd be displacement or something aye? I dont know i hate motion so much, and suck at it. Had my half yearly today, don't know why i studied, or did all of the homework for both topics.. or cared at all, cos there's no chance ill pass it.
rama_v
Active Member
13--19 = 32....I think thats this question works.
DementedDonkey
Member
- Joined
- Jul 2, 2004
- Messages
- 102
- Gender
- Female
- HSC
- 2005
hmmm... i'm not sure. I have a feeling that you cant just do that with velocities..but hey for some reason we got the same answer.... im totally lost, this is the point where i check the answer in the back of the book
rama_v
Active Member
Sorry for confusion
lol sorry I haven't donr those problems in a while, thats prelim stuff. Sorry every1 for the confusion I better butt out
lol sorry I haven't donr those problems in a while, thats prelim stuff. Sorry every1 for the confusion I better butt out
Last edited: