Experimental Evidence.
Scientists conduct experiments or observations to gather evidence that either support or disprove a given hypothesis. Hence, all the scientific explanations are based on this body of observations.
 
        
                    
             
        
        
        
Answer:
Option C - 39.2 J
Explanation:
We are given that;
Mass; m = 2 kg.
Distance moved off the floor;d = 10 m.
Acceleration due to gravity;g = 9.8 m/s².
We want to find the work done. 
Now, the Formula for work done is given by;
Work = Force × displacement.
In this case, it's force of gravity to lift up the boots, thus;
Formula for this force is;
Force = mass x acceleration due to gravity
Force = 2 × 9.8 = 19.2 N
∴ Work done = 19.6 × 2
Work done = 39.2 J.
Hence, the Work done to life the boot of 2 kg to a height of 2 m is 39.2 J.
 
        
                    
             
        
        
        
Answer:
945 j
Explanation:
You have just given the ball kinetic energy, which is given by the following equation:
KE= 1⁄2 m v2 = 1⁄2 (2.1 kg)(30 m/s)2 = 945 Joules 
 
        
             
        
        
        
Answer:
0.25 m
Explanation:
Electromagnetic waves consist of oscillations of the electric and the magnetic field, oscillating in a plane perpendicular to the direction of motion the wave.
All electromagnetic waves travel in a vacuum always at the same speed, the speed of light, whose value is:
 
Microwave is an example of electromagnetic waves.
The relationship between wavelength and frequency for an electromagnetic wave is:

where
 is the wavelength
 is the wavelength
 is the speed of light
  is the speed of light
f is the frequency
For the microwave in this problem,

So its wavelength is

 
        
             
        
        
        
<h2>The work done = - 2 x 10⁴ J</h2>
Explanation:
In the first case , the volume is kept constant and pressure varies . 
In isothermal process  , the work done 
W₁ = V x ΔP
here V is the volume of gas and ΔP is the change in pressure 
Thus W₁ = 0
Because there is no change in volume , therefore displacement is zero .
In second case pressure is constant , but volume changes 
Thus W₂ = P x ΔV
here P is the pressure  and ΔV is the change in volume 
Therefore W₂ = 4 x 10⁵ x 5 x 10⁻² = 2 x 10⁴ J
The total work done W = - 2 x 10⁴ J
Because the work done in compression is negative .