Physics help plz!!!! Here's some of the problems to understand the concepts(motion

[lisa rowe]

in 2D and 3D). Thank you! These are some of the problems for my AP Physics class. If you know them, please explain & show equations so that I understand. Thank you.

1)[PROJECTION MOTON ANALYZED]A projectile's launch speed is five times its speed at maximum height. Find launch angle.

2)[UNIFORM CIRCULAR MOTION]What is the magnitude of the acceleration of a sprinter running at 10 m/s when rounding a turn of a radius 25m?

ADDITIONAL

3)A 200m wide river flows due east at a uniform speed of 2 m/s. A boat with speed 8 m/s relative to the water leaves the south bank pointed in a direction 30 degrees west of north. Whats a)the magnitude b)direction of the boat's velocity relative to the ground? c) How long does it take the boat to cross the river?

4) a)What is the magnitude of the centripetal acceleration of an object on Earth's equator due to the rotation of Earth? b)What would Earth's rotation period have to be for objects on the equator to have a centripetal acceleration of magnitude 9.8 m/s² ?