1. It’s true
4 ,7 ,8 is correct
Its tangential speed is constant although its velocity is changing. As the object changes direction, it results in a changing of positive and negative signs of the velocity. Although, the magnitude of the velocity (speed) is not changing.
The solution for this problem is through this formula:Ø = w1 t + 1/2 ã t^2
where:Ø - angular displacement w1 - initial angular velocity t - time ã - angular acceleration
128 = w1 x 4 + ½ x 4.5 x 5^2 128 = 4w1 + 56.254w1 = -128 + 56.25 4w1 = 71.75w1 = 71.75/4
w1 = 17.94 or 18 rad s^-1
w1 = wo + ãt
w1 - final angular velocity
wo - initial angular velocity
18 = 0 + 4.5t t = 4 s
The work done is 375 J
Explanation:
The work done by a force in moving an object is given by

where
F is the magnitude of the force
d is the displacement
is the angle between the direction of the force and the displacement
In this problem,
F = 75 N is the force applied to the couch
d = 5 m is the displacement
Assuming the force applied to the couch is parallel to the motion, 
And so, the work done is

Learn more about work:
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By putting this special transportation plastic on the bottom of the sled, because the transportation plastic is slick. that is what the transport bins slide around on. (p.s) the plastic is really expensive!