Average velocity is different than average speed because calculating average velocity involves considering the direction the bodies are moving.
When calculating average speeds you don't have to consider directions of the bodies.
This is because velocity is a vector quantity which must be defined by direction. Speed is a scalar quantity thus it does not have to be defined by direction.
Newton stated 3 laws that rules moving bodies:
First law - an object remains in its state (resting or moving at constant speed) unless acted upon a force
Second law - the force (F) of an object is equal to its mass (m) multiplied by its acceleration (a); F = m x a
Third law - when an object exerts a force upon another, the second object exerts a force that is equal in magnitude and opposite in direction
So, according to the First Law of Motion, the metor moving through outer space will continues its motion until an outside force acts upon it
Answer:
the answer is B. it's too easy
Answer:
20N
Explanation:
The force (Hooke's Law) is proportional to the deformation. To extend the spring 4 times longer, you will need 4 times the force. In total, 20 N
Apply conservation of angular momentum:
L = Iw = const.
L = angular momentum, I = moment of inertia, w = angular velocity, L must stay constant.
L must stay the same before and after the professor brings the dumbbells closer to himself.
His initial angular velocity is 2π radians divided by 2.0 seconds, or π rad/s. His initial moment of inertia is 3.0kg•m^2
His final moment of inertia is 2.2kg•m^2.
Calculate the initial angular velocity:
L = 3.0π
Final angular velocity:
L = 2.2w
Set the initial and final angular momentum equal to each other and solve for the final angular velocity w:
3.0π = 2.2w
w = 1.4π rad/s
The rotational energy is given by:
KE = 0.5Iw^2
Initial rotational energy:
KE = 0.5(3.0)(π)^2 = 14.8J
Final rotational energy:
KE = 0.5(2.2)(1.4)^2 = 21.3J
There is an increase in rotational energy. Where did this energy come from? It came from changing the moment of inertia. The professor had to exert a radially inward force to pull in the dumbbells, doing work that increases his rotational energy.
