Answer:
Explanation:
change in momentum = m ( v - u ) ; m is mass , V is final velocity and u is initial velocity .
= 250 ( 28 - 6 )
= 5500. N.s
for calculating magnitude of force we shall apply the concept of impulse
Impulse = F X t = m( v-u ) ; F is force applied for time t .
F x 60 = 5500
F = 91.67 N .
force exerted = 91.67 N .
Answer:
a) 
b) 
Explanation:
Part a
For this case we can begin finding the period like this:

Then we know that the centripetal acceleration is given by:

And the velocity is given by:

If we replace this into the acceleration we got:

And we can replace the values and we got:

Part b
For this case we want to find a value of k such that:

Where a = 9.74, so then we can solve for k like this:

Answer:12.8 ft/s
Explanation:
Given
Speed of hoop 
height of top 
Initial energy at bottom is

Where m=mass of hoop
I=moment of inertia of hoop
=angular velocity
for pure rolling 



Energy required to reach at top


Thus 512.2 m is converted energy is spent to raise the potential energy of hoop and remaining is in the form of kinetic and rotational energy

Therefore



A hard rubber plastic comb is made out of rubber so it doesn't conduct electricity. This means that it is an insulator. Unlike a conductor (a metal comb), an insulator keeps the electrons at the place of where it was rubbed instead of equally distributing them around the surface of the comb.
In a metal comb, the charges within the comb move around while in the rubber comb they can't move around because in an insulator, it doesn't allow the movement of charges.
Radio waves have longer wavelengths and lower frequencies than microwaves.
infrared is longer wavelengths and lower frequencies than UV light