Answer:
7500 m
Explanation:
The radar emits an electromagnetic wave that travels towards the object and then it is reflected back to the radar.
We can call L the distance between the radar and the object; this means that the electromagnetic wave travels twice this distance, so
d = 2L
In a time of
Electromagnetic waves travel in a vacuum at the speed of light, which is equal to
Since the electromagnetic wave travels with constant speed, we can use the equation for uniform motion ,so:
(1)
where
, where L is the distance between the radar and the object
Re-arranging eq(1) and substituting, we find L:
The velocity is a vectorial quantity, whereas speed is a scalar quantity, meaning it depends on the direction!
As such, the velocity is changing because the direction is changing.
Answer:
The best time to view the spectacle on Dec. 21 will be around an hour after sunset.
The man is holding the suitcase at the same height above the surface of earth. So the gravitation potential energy remains the same.
<span>work done is force * displacement = weight * 0 = 0</span>
<u>Answer:</u>
At time 2t the paint ball is at 8 cm to the right and 16 cm to the bottom
<u>Explanation:</u>
We have equation of motion , 
, s is the displacement, u is the initial velocity, a is the acceleration and t is the time.
Considering the horizontal motion of paint ball
Distance traveled during time t = 4 cm
Initial velocity = u m/s
Acceleration = 0 
So 
Now at time 2t,
So horizontal distance traveled in time 2t = 8 cm to the right
Now considering the vertical motion of paint ball
Distance traveled during time t = 4 cm
Initial velocity = 0 m/s
Acceleration = -g
At time 2t,
So vertical distance traveled in time 2t = 16 cm to the bottom
