Answer:
A reference point.
Explanation:
Reference point:
A reference point is a point which is used to determine weather the object is in motion or not. The moving object is compared with the reference point.
An object is in the state of motion when its distance is changed relative to the other object or reference point.
In order to determine weather an object is moving or not a point of reference is needed.
Without reference point displacement can not be measured
Answer:
<em>2.085 x 10^-20 J</em>
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Explanation:
minimum energy required to produce photoelectric effect in chromium is given as hf = 7.21 x 10^-19 J
The work function of chromium Ф = 4.37 eV = 7.00151 x 10^-19 J
The minimum energy required to eject an electron from from a chromium metal E = ?
From E = hf - Ф
substituting values, we have
E = (7.21 x 10^-19) - (7.00151 x 10^-19)
E = <em>2.085 x 10^-20 J</em>
Answer:
Aluminium (Al): (3*2)+(5*2)=16
Sulphor (S): (3*1)=3
Oxygen (O): (4*3)+(3*1)=15
There are 1000 mg in 1 g
and there are 1000 g in 1 kg
Start by converting 1.34 mg to grams by dividing 1.34 mg by 1000 g = 0.00134 g
Then convert 0.00134 g to kg by dividing 0.00134 g by 1000 kg = 1.34×10^-6 kg OR 0.00000134 kg
it will take john 3 hours to reach his destination
1 hour = 52 miles x 3 = 156 miles
