C is the correct answer, hope it helps
The Doppler Effect...
<span>It describes an increase (or decrease) in the frequency of sound, light, or other waves as the source and observer move toward (or away from) each other.</span>
Answer:
B
Explanation:
Friction acts in a direction opposite to the motion of an object
The weight of an object is taken to be the force on the object due to gravity. The weight ( W ) is the product of the mass ( m ) of the object and the magnitude of the gravitational acceleration ( g ).
On Earth: g = 9.81 m/s²
m = 20 kg
W = m · g = 20 kg · 9.81 m/s² = 196.2 N
