Answer:
-0.0047 rad/s²
335.103 seconds
99.18 seconds
Explanation:
= Final angular velocity
= Initial angular velocity = 1.5 ra/s
= Angular acceleration
= Angle of rotation = 40 rev
t = Time taken
Equation of rotational motion
Acceleration while slowing down is -0.0047 rad/s²
Time taken to slow down is 335.103 seconds
Solving the equation
The time required for it to complete the first 20 is 99.18 seconds as 539.11>335.103
Answer:
7.9 m/s
Explanation:
When both balls collide, they have spent the same time for their motions.
Motion of steel ball
This is purely under gravity. It is vertical.
Initial velocity, <em>u </em>= 0 m/s
Distance, <em>s</em> = 4.0 m - 1.2 m = 2.8 m
Acceleration, <em>a</em> = g
Using the equation of motion
Motion of plastic ball
This has two components: a vertical and a horizontal.
The vertical motion is under gravity.
Considering the vertical motion,
Initial velocity, <em>u </em>= ?
Distance, <em>s</em> = 1.2 m
Acceleration, <em>a</em> = -<em>g </em> (It is going up)
Using the equation of motion
Substituting the value of <em>t</em> from the previous equation,
Taking <em>g</em> = 9.8 m/s²,
This is the vertical component of the initial velocity
Considering the horizontal motion which is not accelerated,
horizontal component of the initial velocity is horizontal distance ÷ time.
The initial velocity is