Answer:
petroleum and Natural gas are fossil fuels
Explanation:
 
        
             
        
        
        
wavelength of the EM  wave produced by your iclicker is 0.33 m.
<h3>What makes an EM wave?</h3>
- When an electric field (illustrated in red arrows) combines with a magnetic field, electromagnetic waves are generated (which is shown in blue arrows). An electromagnetic wave's magnetic and electric fields are perpendicular to each other and to the wave's direction.
- A changing magnetic field causes a changing electric field, and vice versa—the two are inextricably related. Electromagnetic waves are created by changing fields. Electromagnetic waves, unlike mechanical waves, do not require a medium to propagate.
The clicker emits EM (electromagnetic) wave which travels at the speed of light, that is
v = 3 x 10⁸ m/s
The frequency is
f = 900mHz = 9 x 10⁸ Hz
 velocity = frequency * wavelength, the wavelength, λ,  is given by
fλ = v
λ = v/f
   = (3 x 10⁸ m/s) / (9 x 10⁸ 1/s)
   = 1/3 m = 0.333 m
To learn more about   electromagnetic waves  refer,
brainly.com/question/25847009
#SPJ1
 
        
             
        
        
        
Answer:
a) m = 69.0 kg
b) release some gas in the opposite direction to the astronaut's movement 
Explanation:
a) Let's use Newton's second law
          F = m a
          m = F / a
          m = 60.0 / 0.870
          m = 69.0 kg
b) when we exert a force on the astronaut it acquires a momentum po, as the astronaut system plus spacecraft is isolated, the momentum is conserved
          p₀ = p_f
          m v = M v '
          v ’=  
so we see that the ship is moving backwards, but since the mass of the ship is much greater than the mass of the astronaut, the speed of the ship is very small.
One method to avoid this effect is to release some gas in the opposite direction to the astronaut's movement so that the initial momentum of the astronaut plus the gas is zero and therefore no movement is created in the spacecraft.