As per the question, the distance travelled by bobsled [s] = 100 m
The time taken by the bobsled to travel that distance [t] = 25 s
We are asked to calculate the speed of the bobsled.
The speed of the bobsled is calculated as -
                                             
                                             
                                                    
                                                    
Hence, the correct answer to the question is A. 4 m/s.   
 
        
             
        
        
        
Answer:
Explanation:
Given
mass of book(m)=2.1 kg
height up to which book is lifted is (h)2.2 m
height of person 
Potential energy of book relative to ground=mgh

(b)PE w.r.t to person head =mg(h-h0)

work done by person in lifting box 2.2 m w.r.t floor
Word done =Potential Energy of box relative to floor=45.2 J
 
        
             
        
        
        
Answer:
C. Sleep Apnea
Explanation:
Sleep Apnea is when someone who snores and stops breathing while sleeping 
 
        
             
        
        
        
Answer:
2. The hydrogen atom has quantized energy levels.
Explanation:
The Bohr model of the atom states that the structure of the atom is quantized, that is, that electrons can only orbit the nucleus in specific orbits with a fixed radius. Therefore, the electron cannot be in energy levels that do not correspond to these quantized levels.