Any change in velocity is called an acceleration. The rock is experiencing the gravitational force from the earth, accelerating it towards the ground.
The solution for this problem is:
Remember that this doesn’t depend on the mass of the child.
E = T + U = constant
E (maximum height) = T + U =U = mgh = mg[r - r· cos (Θ)]
E (bottom height) = T + U = T = ½mv² = mg[r - r · cos (Θ)]
v² = 2g[r – r · cos (Θ)]
v = √ (2g[r-r·cos(Θ)])
= √(2(9.8)[3 – 3 · cos (45°)])
= 4.15 m/s or 15 kph
In navigation bearing refers to : 1. the direction of motion itself; 2. the direction of a distant object relative to the current course 3.the angle away from North of a distant point as observed at the current point.
There is a thing called absolute bearing, and it refers to the angle between the magnetic North/true North and an object. (e.g. an object of 0 degrees would be dead ahead, whereas and object of 180 degrees would be behind you)