Explanation:
Given parameters:
Distance hopped = 84m
Displacement = 84m due east
Time = 7s
Unknown:
Speed of kangaroo = ?
Velocity of kangaroo = ?
Solution:
To solve this problem,
Speed = 
= 
= 12m/s
Velocity = 
= = 12m/s due east
The ball accelerates because of gravity.
Relative to the positive horizontal axis, rope 1 makes an angle of 90 + 20 = 110 degrees, while rope 2 makes an angle of 90 - 30 = 60 degrees.
By Newton's second law,
- the net horizontal force acting on the beam is
where 
are the magnitudes of the tensions in ropes 1 and 2, respectively;
- the net vertical force acting on the beam is
where 
and 
.
Eliminating 
, we have
Solve for .
Answer:
V (initial vertical velocity) = 45.4 sin 31.2 = 23.52 m/s
1/2 m V^2 = m g h conservation of energy
h = V^2 / (2 g) = 23.52^2 / 19.6 = 28.2 m max height
Check:
t = 28.2 / 9.8 = 2.88 sec time to reach max height
h = 23.52 * 2.88 - 1/2 g 2.88^2 = 27.1 m
A rotating disc supplied with constant power where the relationship of the angular velocity of the disc and the number of rotations made by the disc is governed by Newton's second law for rotation. This law is specially made for rotating bodies which is extracted from Newton's second law of motion.
