Answer: 0 km/h
Explanation:
As a vector, the plane's velocity is 100 km/h (west) - 100 km/h (east) = 0 km/m.
To an observer on the ground, the plane will be standing still.
Answer:
If an object moves twice as fast its kinetic energy quadruples.
Explanation:
The kinetic energy (K₁) of a body of mass (m) that moves with speed (v) is:
K₁= 1/2 * m* v²
If we double the speed of the body, its kinetic energy (K₂) will be:
K₂= 1/2 * m*( 2v)²
K₂= 1/2 * m* 4 *v²
K₂= 4(1/2 * m *v²)
K₂= 4*K₁
Answer:
a. chemical reaction
Explanation:
In both a dry and wet cell battery, electric currents are produced through chemical reactions.
Both cells are together called electrochemical cells.
- In these cells, chemical reactions produce an electric current.
- They are devices that converts chemical energy into electrical energy
- The reactions here are spontaneous redox reactions.
- This causes the current to flow on their own in the circuit.
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Answer: Doppler effect
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Explanation:
A radar gun (also known as a Doppler radar) uses the Doppler effect when measuring "return echoes" after having sent a microwave signal (a type of electromagnetic radiation).
In this context the Doppler effect consists of the change in a wave perceived frequency when the emitter of the waves, and the observer move relative to each other.
In the case of radars, a microwave signal is sent to a target (the tennis or baseball in this case) and then is reflected after "hitting" the target, so that the radar system measures this difference between the sent signal and the reflected signal.
The answer is b. Electromagnetic waves do not need a medium to travel through.
