Has a skateboard. your gonna have to give more details the. that just one .
(a) 1200 rad/s
The angular acceleration of the rotor is given by:

where we have
is the angular acceleration (negative since the rotor is slowing down)
is the final angular speed
is the initial angular speed
t = 10.0 s is the time interval
Solving for
, we find the final angular speed after 10.0 s:

(b) 25 s
We can calculate the time needed for the rotor to come to rest, by using again the same formula:

If we re-arrange it for t, we get:

where here we have
is the initial angular speed
is the final angular speed
is the angular acceleration
Solving the equation,

Answer:
the initial velocity of the ball is 104.67 m/s.
Explanation:
Given;
angle of projection, θ = 60⁰
time of flight, T = 18.5 s
let the initial velocity of the ball, = u
The time of flight is given as;

Therefore, the initial velocity of the ball is 104.67 m/s.
Answer:
Correct answer: C. 50 cm
Explanation:
Given data:
The distance of the object from the top of the concave mirror o = 50.0 cm
The magnitude of the concave mirror focal length 25.0 cm.
Required : Image distance d = ?
If we know the focal length we can calculate the center of the curve of the mirror
r = 2 · f = 2 · 25 = 50 cm
If we know the theory of spherical mirrors and the construction of figures then we know that when an object is placed in the center of the curve, there is also a image in the center of the curve that is inverted, real and the same size as the object.
We conclude that the image distance is 50 cm.
We will now prove this using the formula:
1/f = 1/o + 1/d => 1/d = 1/f - 1/o = 1/25 - 1/50 = 2/50 - 1/50 = 1/50
1/d = 1/50 => d = 50 cm
God is with you!!!