The answer is (A) the object must be at rest.
When all of the forces acting on an object balance, the net force is zero and hence the object will not move.
Yes, the direction might also change under some special circumstances.
Answer:
Sound wave types - longitudinal waves
Longitudinal waves - Vibrating string the creates sound in the way it moves.
Explanation:
Longitudinal waves have particles of the medium that are displaced in a parallel direction to energy transport.
Answer:
D. The temperature does not change during a phase change because the average kinetic energy does not change. Therefore, the potential energy in the bonds between molecules must change.
Explanation:
When there is a change of state (for example, from solid into a liquid, as in this example), when energy is added to the system, the temperature of the substance does not change.
The reason for this is that the energy supplied is no longer used to increase the average kinetic energy of the particle, but instead it is used to break the bonds between the different particles/molecules. For instance, since in this case the substance is changing from solid to liquid, all the energy supplied during the phase change is used to break the bonds between the molecules of the solid: when the process is done, all the molecules will be free to slide past each other, and the substance has turned completely into a liquid.
The bonds between molecules store potential energy: therefore, this means that the energy supplied during the phase change is not used to change the kinetic energy, but to change the potential energy in the bonds between the molecules.
Answer:
Explanation:
d = Diameter of spot = 30 μm
r = Radius of spot = 
P = Power of the laser = 
A = Area = 
Intensity is given by
The light intensity within this spot is 
