Answer:
890 N
Explanation:
Acceleration is change in velocity over change in time.
a = Δv / Δt
a = (11 m/s − 0 m/s) / 0.26 s
a = 42.3 m/s²
Force is mass times acceleration.
F = ma
F = (21 kg) (42.3 m/s²)
F ≈ 890 N
 
        
             
        
        
        
Answer:
The change in temperature is  
 
Explanation:
From the question we  are told that 
    The temperature coefficient is  
The resistance of the filament is mathematically represented as 
            ![R  =  R_o [1 + \alpha  \Delta T]](https://tex.z-dn.net/?f=R%20%20%3D%20%20R_o%20%5B1%20%2B%20%5Calpha%20%20%5CDelta%20T%5D)
Where  is the initial resistance
 is the initial resistance 
Making the change in temperature the subject of the formula 
      ![\Delta T = \frac{1}{\alpha } [\frac{R}{R_o} - 1 ]](https://tex.z-dn.net/?f=%5CDelta%20T%20%3D%20%5Cfrac%7B1%7D%7B%5Calpha%20%7D%20%5B%5Cfrac%7BR%7D%7BR_o%7D%20-%201%20%5D)
 Now from ohm law 
            
This implies that current varies inversely with current so
            
Substituting this we have 
        ![\Delta T  = \frac{1}{\alpha } [\frac{I_o}{I} - 1 ]](https://tex.z-dn.net/?f=%5CDelta%20T%20%20%3D%20%5Cfrac%7B1%7D%7B%5Calpha%20%7D%20%5B%5Cfrac%7BI_o%7D%7BI%7D%20-%201%20%5D)
From the question we are told that 
     
Substituting this we have 
    ![\Delta T  = \frac{1}{\alpha } [\frac{I_o}{\frac{I_o}{8} } - 1 ]](https://tex.z-dn.net/?f=%5CDelta%20T%20%20%3D%20%5Cfrac%7B1%7D%7B%5Calpha%20%7D%20%5B%5Cfrac%7BI_o%7D%7B%5Cfrac%7BI_o%7D%7B8%7D%20%7D%20-%201%20%5D)
=>     
          
 
 
        
             
        
        
        
If no frictional work is considered, then the energy of the system (the driver at all positions is conserved.
Let 
position 1 = initial height of the diver (h₁), together with the initial velocity (v₁).
position 2 = final height of the diver (h₂) and the final velocity (v₂).
The initial PE = mgh₁ and the initial KE  = (1/2)mv₁²
where g = acceleration due to gravity,
m = mass of the diver.
Similarly, the final PE and KE are respectively mgh₂ and (1/2)mv₂².
PE in position 1 is converted into KE due to the loss in height from position 1 to position 2. 
Therefore
(KE + PE) ₁ = (KE + PE)₂
Evaluate the given answers.
A) The total mechanical energy of the system increases.
     FALSE
B) Potential energy can be converted into kinetic energy but not vice versa.
     TRUE
C) (KE + PE)beginning = (KE + PE) end.
     TRUE
D) All of the above.
     FALSE
 
        
        
        
Water is, indeed, an exception. Normally when temperature drops, material shrinks. Water doesn't, water expands instead.