Answer:
some kind of chemical of which i do not know
Explanation:
 
        
             
        
        
        
Complete Question 
An airplane takes off a runway at a constant speed of 49 m/s at constant angle 30 to the horizontal.How high (in meters )  is the airplane above the ground 13 seconds after takeoff?
Answer:
The height  is 
Explanation:
From the question we are told that 
    The speed at which the plane takes off is  
       The angle at which it takes off is  
         The time taken is 
The vertical distance traveled is  mathematically represented as
           
Substituting values   
          
         
 
        
             
        
        
        
Answer: 
Explanation:
The equation to calculate the center of mass  of a particle system is:
 of a particle system is:

In this case we can arrange for one dimension, assuming the geometric center of the Earth and the ladder are on a line, and assuming original center of mass located at the Earth's geometric center:

Where:
 is the mass of the Earth
 is the mass of the Earth
 is the mass of 1 billion people
 is the mass of 1 billion people
 is the radius of the Earth
 is the radius of the Earth
 is the distance between the center of the Earth and the position of the people (2 m above the Earth's surface)
 is the distance between the center of the Earth and the position of the people (2 m above the Earth's surface)

 This is the displacement of Earth's center of mass from the original center.
 This is the displacement of Earth's center of mass from the original center.
 
        
             
        
        
        
Answer:
1.3 × 10⁸ e⁻
Explanation:
When a honeybee flies through the air, it develops a charge of +20 pC = + 20 × 10⁻¹² C. This is a consequence of losing electrons (negative charges). The charge of 1 mole of electrons is 96468 C (Faraday's constant). The moles of electrons representing 20 pC are:
20 × 10⁻¹² C × (1 mol e⁻/ 96468 C) = 2.1 × 10⁻¹⁶ mol e⁻
1 mole of electrons has 6.02 × 10²³ electrons (Avogadro's number). The electrons is 2.1 × 10⁻¹⁶ moles of electrons are:
2.1 × 10⁻¹⁶ mol e⁻ × (6.02 × 10²³ e⁻/ 1 mol e⁻) = 1.3 × 10⁸ e⁻
 
        
             
        
        
        
Https://answers.yahoo.com/question/index?qid=20120227184717AAzEq8g