Answer:
4.5kgm/s
Explanation:
Change in momentum is expressed as
Change in momentum = m(v-u)
M is the mass
V is the final velocity
u is the initial velocity
Given
m=0.45kg
v = 30m/s
u = 20m/s
Substitute
Change in momentum = 0.45(30-20)
Change in momentum = 0.45×10
Change in momentum = 4.5kgm/s
Answer:
D. 4000 km
Explanation:
f = Frequency of wave that is being transmitted = 76 Hz
= Wavelength of wave that is being transmitted
v = The velocity of electromagnetic waves through air = 
Velocity of a wave is given by

Hence, the approximate wavelength of the waves is 4000 km
Answer:
20.7N
Explanation:
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As a wave moves through a medium, particles are displaced and return to their normal position after the wave passes.
Explanation:
A wave is a traveling disturbance that carries energy from one location to another. All waves move in straight lines outward and away from the source of a disturbance. Like the radiating circular ripples, the waves of water carry energy away from where a rock was dropped into the pond.
Waves can move as a single pulse or as a continuous series of waves, carrying energy away from its source. A pulse is a single disturbance, wave, or ripple that moves outward from the point of disturbance. A train of waves are many waves emitted over and over again from a single source.
As waves travel through matter, they will temporarily displace the molecules or particles in matter up-and-down or side-to-side. Waves move the energy but they do not carry the matter with them longitudinally as they move through matter. Once the disturbance passes, the medium will return to its original state or position.
Therefore, as the waves move through a medium, particles are displaced and return to their normal position after the wave passes.