physics

Q1.temperature rises係咪因為increase of kinetic energy??例如do work將chemical energy變成kinetic energy,heating將一件物體既kinetic energy 傳到另一件,係咪咁樣？
The kinetic energy of particles in a substance is manifested as its temperature. The higher the temperature indicates the larger the avergae kinetic energy of the particles.
Q2.書度話 temperature difference 大conduction就會快,咁如果A一邊係90度,一邊係20度,而B一邊係90度,另一邊係10度,咁邊個conduction會快d??
If the two objects are identical, i.e. they are of same material substance and with the same geometrical dimensions, then a larger temperature difference between the two ends causes a higher rate of heat flow.

Q3.點解acceleration既單位係ms^-2?
Acceleration is the rate of change of velocity.
The unit for velocity, and thus 'change of velocity', is m/s
Rate of change of velocity means the 'change of velocity in 1 second'. i.e. how many m/s in 1 s, or [m/s]/s = m/s2
Q4.if the deceleration of a car is halved, the stopping distance will not be doubled.點解？please illustrate the point with equations of motions
Use the equation: v^2 = u^2 + 2.a.s
where v = 0 m/s when the car comes to a stop.
thus, s = u^2/2a
Suppose a car with decceleration of a/2, then the stopping distance s' is,
s' = u^2 /2(a/2) = u^2/a = 2s
The stopping distance is doubled.
However, if you take into account the reaction time of the driver, a constant needs to be added to the stopping distance. Then the new stopping distance is less than doubled.