A woman on a bridge 89.6 m high sees a raft floating at a constant speed on the

Question

A woman on a bridge 89.6 m high sees a raft floating at a constant speed on the river below. She drops a stone from rest in an attempt to hit the raft. The stone is released when the raft has 8.25 m more to travel before passing under the bridge. The stone hits the water 5.51 m in front of the raft. Find the speed of the raft.

Explanation / Answer

Take the question in two shifts ==========================Women dropping a stone initial velocity of stone, u = 0m/s height from where stone is dropped, h = 89.6m acceleration = 9.8m/s^2 BY newton;s laws of motion, v^2=u^2 + 2as => v^2 = 2 x 9.8 x 89.6 => v^2 = 1489.6 => v = 41.9m/s By newton's laws of motion, v = u +at => t = (v-u)/a => t = 41.9/9.8 => t = 4.276s the time taken by stone is equal to the time taken by the raft to move from being 8.25m away from bridge to 5.51m ================================motion of raft S = 8.25 - 5.51 => S = 2.74m time to travel this distance = 4.276 therefore speed of raft = s/t = 2.74/4.276 = 0.64m/s.

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.