While a roofer is working on a roof that slants at 36.0 degree above the
horizontal, he accidentally nudges his 95.0N toolbox, causing it to start sliding
downward, starting from rest.
If it starts 4.40m from the lower edge of the roof, how fast will the toolbox be
moving just as it reaches the edge of the roof if the kinetic friction force on it
is 18.0N ?
? m/s
toolbox
2012-10-20 3:42 am
回答 (1)
2012-10-20 7:34 am
✔ 最佳答案
Potential energy of toolbox when released = 95 x 4.4.sin(36) J = 245.69 JWork done against friction = 18 x 4.4 J = 79.2 J
Use conservation of mechanical energy.
245.69 = (1/2).(95/g)v^2 + 79.2
where v is the speed of the toolbox at the edge of the roof, and g is the acceleration due to gravity, taken to be 10 m/s^2
hence, v = 5.92 m/s
收錄日期: 2021-04-29 17:46:53
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20121019000051KK00455