Answer:
When her hands extends, her momen of inertia is
.
Explanation:
Given that,
Initial angular speed, 
Initial moment of inertia, 
Final angular speed, 
Initially, a skater rotates with her arms crossed and finally she extends her arms. The momentum remains conserved. Using the conservation of momentum as :

is final moment of inertia

So, when her hands extends, her momen of inertia is
. Hence, this is the required solution.
Answer:
<em>The velocity after the collision is 2.82 m/s</em>
Explanation:
<u>Law Of Conservation Of Linear Momentum
</u>
It states the total momentum of a system of bodies is conserved unless an external force is applied to it. The formula for the momentum of a body with mass m and speed v is
P=mv.
If we have a system of two bodies, then the total momentum is the sum of the individual momentums:

If a collision occurs and the velocities change to v', the final momentum is:

Since the total momentum is conserved, then:
P = P'
Or, equivalently:

If both masses stick together after the collision at a common speed v', then:

The common velocity after this situation is:

There is an m1=3.91 kg car moving at v1=5.7 m/s that collides with an m2=4 kg cart that was at rest v2=0.
After the collision, both cars stick together. Let's compute the common speed after that:



The velocity after the collision is 2.82 m/s
Answer:
KE=800,000
Explanation:
The formula for kinetic energy is KE=1/2mv^2 or Kinetic Energy= 0.5*mass*velocity^2
so 1000 is the mass and 40 is the velocity
KE=0.5*1000*40^2
KE=0.5*1,000*1,600
KE=800,000 Joules
Answer:
<em>the phase relationship between two waves.</em>
<em></em>
Explanation:
Coherence describes all properties of the correlation between physical quantities between waves. It is an ideal property of waves that determines their interference. In a situation in which there is a correlation or phase relationship between two waves. If the properties of one of the waves can be measure directly, then, some of the properties of the other wave can be calculated.