Answer:
A new substance was formed
Explanation:
According to this question, a shiny and flexible metal called Magnesium (Mg) is burnt in air to produce a white powder that has no shiny or flexible properties, however, has more weight than the magnesium metal itself. 
This is possible because a CHEMICAL CHANGE has occured, hence, a new substance has been formed. The formation of a new substance during the burning process (chemical reaction), induced the increase in mass. 
 
        
             
        
        
        
For the first hour, the slope is zero.
After that, the slope is -2 miles per hour.
 
        
             
        
        
        
Answer:
The required angle is (90-25)° = 65°
Explanation:
The given motion is an example of projectile motion.
Let 'v' be the initial velocity and '∅' be the angle of projection.
Let 't' be the time taken for complete motion.
Let 'g' be the acceleration due to gravity
Taking components of velocity in horizontal(x) and vertical(y) direction.
 =  v cos(∅)
 =  v cos(∅) 
 =  v sin(∅)
 =  v sin(∅)
We know that for a projectile motion,
t =
Since there is no force acting on the golf ball in horizonal direction.
Total distance(d) covered in horizontal direction is -
d =  ×t = vcos(∅)×
×t = vcos(∅)× =
 =  .
.
If the golf ball has to travel the same distance 'd' for same initital velocity v = 23m/s , then the above equation should have 2 solutions of initial angle 'α' and 'β' such that -
α +β = 90° as-
d =  =
 = ![\frac{v^{2}sin(2[90-β]) }{g}](https://tex.z-dn.net/?f=%5Cfrac%7Bv%5E%7B2%7Dsin%282%5B90-%CE%B2%5D%29%20%7D%7Bg%7D) =
 = =
 =  .
 .
∴ For the initial angles 'α' or 'β' , total horizontal distance 'd' travelled remains the same.
∴ If α = 25° , then
      β = 90-25 = 65°
∴ The required angle is 65°.
 
        
                    
             
        
        
        
Answer:
Power = 130 watt
Explanation:
Power is described as the ability to do work, it is also defined as the amount of work in Joules done in a given time in seconds. Mathematically, it is represented as:

In this example, power is calculated as follows:
Work = 39000 J
Time = 5 minutes
 converting the time from minutes to seconds:
1 minute = 60 seconds
∴ 5 minutes = 60 × 5 = 300 seconds

N:B the unit for power can also be represented as Joules/seconds or J/s or JS⁻¹