Answer: Your correct main answer is a submarine
Explanation:
Submarines are usually used for underwater warfare, and naval submarines are equipped with torpedoes, missiles, and high-powered nuclear weapons. The use of these along with their advanced tracking system helps to target ships and boats from below as well as other enemies. They can also work on targets that are on land.
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Answer: Because of Inertia
Explanation: According to Newton first law, that a body in a linear motion will continue to be in motion except an external for act on it
But also, a body in motion will always like to continue in motion and have a reluctance tendency to stop because of inertia.
the crash test dummies' bodies will continue to move forward even though the car stopped because of inertia.
To solve this problem we will apply the linear motion kinematic equations, which describe the change in velocity, depending on the acceleration and the distance traveled, that is,

Where,
= Final Velocity
= Initial Velocity
a = Acceleration
h = height
Our values are given as,

Replacing we have,



Therefore the height of the cliff is 121ft
Answer:
yes
Explanation:
The metal is closer than 20 cm to the magnet which is in the magnetic field.
Answer: 529.9 Hz
Explanation:
Here we need to use the Doppler equation, so we have:
f' = f*(v + v0)/(v - vs)
Here, f is the frequency = 500Hz
v is the velocity of the wave, = 334m/s
v0 is the velocity of the observer = 20m/s
vs is the velocity of the source = 0m/s
Then we have:
f' = 500Hz*(334m/s + 20m/s)/(334m/s) = 529.9 Hz