You may confuse two minerals by their colors so using streak is another way for showing their "true colors "
        
             
        
        
        
Answer: Why does the cord of an electric heater not glow while the heating element does? The heating element of the heater is made up of alloy which has very high resistance so when current flows through the heating element, it becomes too hot and glows red. But the resistance of cord which is usually of copper or aluminum is very low so it does not glow.
Explanation:
 
        
             
        
        
        
1.8 is the mechanical advantage of the lever.
<h3>Definition of mechanical advantage</h3>
The theoretical mechanical advantage of a system is the ratio of the force that performs the useful work to the force applied, assuming there is no friction in the system. 
The advantage gained by the use of a mechanism in transmitting force specifically the ratio of the force that performs the useful work of a machine to the force that is applied to the machine.
Mechanical advantage is given by the ratio of the load lifted to the force applied to lift the load.
In this case, Mechanical advantage=L/E where L is the load and E is the effort applied.
Mechanical advantage= 90/50 =1.8
Question-you use a lever to lift a heavy tree branch. you apply a force of 50 n and the lever lifts the branch with a force of 90 n. what is the mechanical advantage of the lever?
To learn more about the Mechanical advantage visit the link
brainly.com/question/16617083
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Answer:
A. 2.36 Newtons
Explanation:
F = GmM/d²
F = 6.673 x 10⁻¹¹(1)(5.98 x 10²⁴) / (1.3 x 10⁷)²
F = 2.36121...
Very poor question design.
   mass of box... 1 significant digit 
         distance... 2 significant digits
mass of earth... 3 significant digits
      value of G... 4 significant digits
Answer precision to 3 significant digits is not justifiable
 
        
             
        
        
        
there here is your answer to your question
Uncertainty in measurements and calculations means difference between actual and measured data. We can say that all measurements have some degree of uncertainty. ... Systematic error (because of error in measuring instrument) 2. Random error (human errors such as- delay in starting, delay in stopping).