1.A baseball is hit with a speed of 28 m/s at an angle of 45.0 . It lands on the

Question

1.A baseball is hit with a speed of 28 m/s at an angle of 45.0 . It lands on the flat roof of a 13.0-m-tall nearby building. If the ball was hit when it was 1.0 m above the ground, what horizontal distance does it travel before it lands on the building?

2.A rescue plane wants to drop supplies to isolated mountain climbers on a rocky ridge 235 m below. The horizontal velocity of the plane is 250 km/h (69.4 m/s). Rescue plane releases the supplies a horizontal distance of 425 m in advance of the mountain climbers.

part A.) What vertical velocity (up or down) should the supplies be given so that they arrive precisely at the climbers' position

part B.) With what speed do the supplies land?

3.)A person going for a morning jog on the deck of a cruise ship is running toward the bow (front) of the ship at 2.2 m/s while the ship is moving ahead at 6.1 m/s .

part A.) What is the velocity of the jogger relative to the water?

part B.) Later, the jogger is moving toward the stern (rear) of the ship. What is the jogger's velocity relative to the water now?

4.)A boat's speed in still water is vBW = 2.00 m/s . The boat is to travel north directly across a river (Figure 1) whose westward current has speed vWS = 1.30 m/s . Determine the speed of the boat with respect to the shore.

Explanation / Answer

1) vo = 28 m/s

theta = 45 degrees

Horizontal component of velocity = vo cos (theta) = 28 cos 45 = 19.8 m/s

Initial vertical component of velocity = voy = vo sin(theta) = 28 sin 45 = 19.8 m/s

Vertical displacement = y = 13.0 -1.0 = 12.0 m

Now, y = voyt + 0.5at^2

12 = 19.8t + 0.5(-9.81)t^2

12 = 19.8t - 4.905t^2

4.905t^2-19.8t + 12 = 0

t = 3.29 s or 0.74 s

We get two values of times because ball will be at this vertical height while going up as well as while coming down. We will take t = 3.29 s as ball can land on roof (at this height) only while coming down

Horizontal distance covered = horizontal velocity x time taken = 19.8 x 3.29 = 6 m

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