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:
Explanation:
KE is directly proportional to the square of velocity / speed.
if speed is 2 times (doubled) the KE will be
= 4 times the original KE
Answer:
20,000 N
Explanation:
First find the acceleration:
a = Δv / Δt
a = (0 − 40 m/s) / 10 s
a = -4 m/s²
Next use Newton's second law to find the force on the car:
F = ma
F = (5000 kg) (-4 m/s²)
F = -20,000 N
According to Newton's third law, the force on the wall is equal and opposite the force on the car.
F = 20,000 N
Answer:
W = 1884J
Explanation:
This question is incomplete. The original question was:
<em>Consider a motor that exerts a constant torque of 25.0 N.m to a horizontal platform whose moment of inertia is 50.0kg.m^2 . Assume that the platform is initially at rest and the torque is applied for 12.0rotations . Neglect friction.
</em>
<em>
How much work W does the motor do on the platform during this process? Enter your answer in joules to four significant figures.</em>
The amount of work done by the motor is given by:
Where I = 50kg.m^2 and ωo = rad/s. We need to calculate ωf.
By using kinematics:
But we don't have the acceleration yet. So, we have to calculate it by making a sum of torque:
=> 
Now we can calculate the final velocity:
Finally, we calculate the total work:
Since the question asked to "<em>Enter your answer in joules to four significant figures.</em>":
W = 1884J
If the sound comes from the right side, the waves reach the right ear before the left ear. if the sound comes from the left side, the waves reach the left ear before the right ear. The difference between the phases of waves reaching both ears is detected by the ears and then interpreted by the brain
