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AP Physics Help!

lil_killer129lil_killer129 Posts: 4,706Registered User Senior Member
edited September 2008 in AP Tests Preparation
6. According to a rule-of-thumb, every five seconds between a lightning flash and the following thunder gives the distance of the storm in miles. Assuming that the flash of light arrives in essentially no time at all, estimate the speed of sound in m/s from this rule.
Post edited by lil_killer129 on

Replies to: AP Physics Help!

  • towerpumpkintowerpumpkin Posts: 1,660Registered User Senior Member
    That gives (1mi/5s)(1609m/mi)=321m/s
  • lil_killer129lil_killer129 Posts: 4,706Registered User Senior Member
    12. A bowling ball traveling with constant speed hits the pins at the end of a bowling lane 16.5 m long. The bowler hears the sound of the ball hitting the pins 2.5 s after the ball is released from his hands. What is the speed of the ball? The speed of sound is 340 m/s.
  • towerpumpkintowerpumpkin Posts: 1,660Registered User Senior Member
    2.5=Ta+Tb, where Ta=time for ball to hit pins and Tb=time for sound of ball hitting to reach the bowler. d=vt, t=d/v, so Tb=16.5/340=.0485s. Ta=2.5-.0485=2.4515s. v=d/t=16.5/2.4515=6.73m/s

    I hope this isn't homework that you haven't even attempted....
  • lil_killer129lil_killer129 Posts: 4,706Registered User Senior Member
    No it isn't homework. This is from my AP review book. I just didn't understand a few problems.
  • towerpumpkintowerpumpkin Posts: 1,660Registered User Senior Member
    Ok...good...I'm surprised that anyone is doing AP review this early, however...
  • lil_killer129lil_killer129 Posts: 4,706Registered User Senior Member
    I have a quiz tomorrow in class about motion and stuff. I wanted more practice.
  • zacsmitty10zacsmitty10 Posts: 1Registered User New Member
    Calculate the average speed in m/s of a complete round-trip in which the outgoing 250 km is covered at 11.6 m/s followed by a 1.0-hour lunch break, and the return 250 km is covered at 17.2 m/s.

    how do u do this
  • fiona_fiona_ Posts: 1,811Registered User Senior Member
    average speed = total distance / total time
    time for outgoing 250 km = 250 x 10^3 m / (11.6 m/s) = 21 551 s = 5.986 h
    time for break = 1 h
    time for return 250 km = 250 x 10^3 m / (17.2 m/s) = 14 534 s = 4.037 h
    total time = 11.02 h

    total distance = 500 km

    avg speed = 500/11.02 = 45.3 km/h = 12.6 m/s
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