Power = energy/time=20/4=5.0
Answer:
it cannot be considered a physical change because it occur from the chemical reaction.
Explanation:
because physical change is the change of the size,volume, density,flexibility. in other words its a change in the outer appearance or change in which we can see or feel without using a tool or a machine
hope it help just my opinion
Explanation:
It is given that,
Mass of concrete pilling, m = 50 kg
Diameter of wire, d = 1 mm
Radius of wire, r = 0.0005 m
Length of wire, L = 11.2
Young modulus of steel, 
The young modulus of a wire is given by :
So, the wire will stretch 0.034 meters. Hence, this is the required solution.
Mechanical advantage = ideal mechanical advantage x efficiency = 3.5 x 0.6 = 2.1
The mechanical advantage of the inclined plane is 2.1
Near the surface of reflection, reflected wave may interfere with incident wave leading to production of constructive and as well as destructive interference. This in turn, can result to resonance as well as enhancement of the sound intensity as the waves of reflection adds to incident wave. Therefore, the girl would higher intensity of reflected waves as compared to incident waves.
Therefore, statement A is correct.
