Question

Answer: 10.12 A key is dropped from a bridge that is 40.0 m bove the water. At the moment the key is released a model boat is 10.5 m away from the bridge and moving towards the bridge with constant velocity. If the key falls directly into the model boat, calculate the Velocity of the boat. Answer: 11. [2pt] Arie is aimed honuntaily a target located 345 m away. The ballet hits the target 25 cm below the aim point. What was the bullet's time of flight? P r oblem what was the speed of the bullet as it emerged from the rifle barrel? Ant 15. 12pt] You throw a ball towards a wall with a speed of 23 5 m/s and at an angle of 32.0 degrees above the horizontal. The wall is located 20.5 m away from the release point of the ball How far above the release point does the ball hit the wall? Answer: PC Go to problem 1111211311411511611711811910][11[12][13] Status : MacBook Air W E

Answer 1

Given

the key is dropped from the bridge of height h = 40.0 m above the water

then the boat is at a distance of s = 10.5 m from the bridge
moving towards where the key falls directly on the boat .

it would happen if both having the same time period that

the time taken to reach the boat by key and time taken for the boat to reach the bridge

from equations of motions

key
s = ut+0.5*at^2
-h = 0*t- 0.5*g*t^2

   t = sqrt(2*h/g) s

   t = sqrt(2*40.0/9.8) s
  
   t = 2.857 s

Boat
from velocity , v = displacement/ time

       v = 10.5/2.857 m/s

       v = 3.675 m/s

so the boat velocity is v = 3.675 m/s