Explanation:
The two postulates of special theory of relativity
Postulate 1: The law of physics are invariant under any of inertial frame of reference.
Postulate 2: The velocity of light is remains same in each ans every frame of reference and independent of relativity.
They are differ from classical mechanics that in classical mechanics there is no change in mass and length in relative velocity but in relativistic mechanics it changes.
These two postulates implements in phenomenon like time dilation , length contraction etc.
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Answer: false
Explanation:
While kilograms are the unit used to measure body mass, the device used is a scale.
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The transfer of heat from the Sun is in the form of thermal radiation (also called infrared radiation)
The transfer of heat at the person’s feet is by thermal conduction. During the day the sand will be hot so if you step on it with bare feet there will be conduction of heat to the feet.
Answer:
(a) 23 m/s, -4 m/s²
(b) Speed is decreasing.
Explanation:
The velocity of the object is given as:
v(t) = 27 - t²
When t = 2 secs, velocity, v(2) becomes:
v(2) = 27 - (2)²
v(2) = 27 - 4
v(2) = 23 m/s
The acceleration is the first derivative of the velocity, dv/dt:
a(t) = dv(t)/dt = -2t
Acceleration after 2 secs, a(2) is:
a(2) = -2*2
a(2) = -4 m/s²
(b) When velocity and acceleration have opposite signs, it means that the velocity and acceleration are in opposite directions, hence, the object is slowing down.
In other words, the speed is decreasing.
