Answer
D.Diffraction
Explanation
Diffraction is a property that is experienced by waves when they come across a barrier when they are in motion.
The ways tends to curve behind the barrier. This is called diffraction of waves.
Now, sound is a wave and it also experience diffraction. . So the brother will be able to hear the sound due to diffraction
Answer:
m = 69.9 kg
Explanation:
The mass and the weight of an object are two different quantities. Mass is basically the amount of matter that is present in a body. It remains same everywhere in the universe and measured in kilograms.
Weight is basically a force. It is the force by which earth attracts everything towards itself. The weight of an object changes from planet to planet, with the change in value of the gravitational acceleration (g).
Therefore, the relation between mass and weight of an object is given by the following formula:
W = mg
m = W/g
where,
m = mass = ?
W = Weight = 685 N
g = 9.8 m/s²
Therefore,
m = (685 N)/(9.8 m/s²)
<u>m = 69.9 kg</u>
Answer:
Measure the brightness of a star through two filters and compare the ratio of red to blue light. Compare to the spectra of computer models of stellar spectra of different temperature and develop an accurate color-temperature relation.
backward movement
because momentum = mass × speed
And mass must be in positive value..
so negative value is speed
which moving backward..
Answer:4.39 s
Explanation:
Given
initial velocity 
acceleration 
velocity acquired by sled in 
time
distance traveled by sled in 
distance traveled in 
time with velocity
----1
substitute the value of in 1
we get
thus 
