Asked by blair
A student throws a set of keys vertically upward to her sorority sister, who is in a window 4.30 m above. The keys are caught 1.30 s later by the sister's outstretched hand.
(a) With what initial velocity were the keys thrown?
_____________ m/s upward
(b) What was the velocity of the keys just before they were caught?
___________ m/s upward or downward
Can someone help me set up ?Or explain it please. Thank you!
(a) With what initial velocity were the keys thrown?
_____________ m/s upward
(b) What was the velocity of the keys just before they were caught?
___________ m/s upward or downward
Can someone help me set up ?Or explain it please. Thank you!
Answers
Answered by
drwls
(a) 4.30 = Vo*t - (g/2) t^2
= Vo*1.3 - (1/2)*9.81*(1.3)^2
Solve for Vo.
1.3*Vo = 4.30 + 8.29 = 12.59 m
Vo = 9.68 m/s
(b) Use conservation of energy
Initial KE - Final KE = M g * 4.30 m
(Vo^2 - Vf^2)/2 = g * 4.30 m
Solve for the final velocity Vf. The keys could be on the way up or down.
= Vo*1.3 - (1/2)*9.81*(1.3)^2
Solve for Vo.
1.3*Vo = 4.30 + 8.29 = 12.59 m
Vo = 9.68 m/s
(b) Use conservation of energy
Initial KE - Final KE = M g * 4.30 m
(Vo^2 - Vf^2)/2 = g * 4.30 m
Solve for the final velocity Vf. The keys could be on the way up or down.
Answered by
عبدو الحناك
ايوه صح كلامك يكبير بس نمره بي انت هابدها ولا اه
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