Answer:
The gravitational attraction of the Sun is what holds the planets in their elliptical orbits. So to explain this the mass effects the motion of the planets because the strength of gravitational force depends of the mass.
Explanation:
 
        
             
        
        
        
Answer:
A 
Explanation:
It is less than the acceleration of the backpack because abs has a greater mass.
 
        
             
        
        
        
Time = (distance) / (speed)
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Time = (450 km) / (100 m/s)
Time = (450,000 m) / (100 m/s)
Time = <em>4500 seconds </em>(that's 75 minutes)
Note: 
This is about HALF the speed of the passenger jet you fly in when you go to visit Grandma for Christmas.
If the International Space Station flew at this speed, it would immediately go ker-PLUNK into the ocean.
The speed of the International Space Station in its orbit is more like 3,100 m/s, not 100 m/s.
 
        
             
        
        
        
Answer:

Explanation:
Using the tension in the spring and the force of the tension can by describe by 
T = kx
, T = mg
Therefore:

With two springs, let, T1 be the tension in each spring,  x1 be the extension of each spring.  The spring constant of each spring is 2k so:


Solve to x1





 
        
             
        
        
        
Answer:
E = 31.329 N/C.
Explanation:
The differential electric field  at the center of curvature of the arc is
 at the center of curvature of the arc is 
  <em>(we have a cosine because vertical components cancel, leaving only horizontal cosine components of E. )</em>
 <em>(we have a cosine because vertical components cancel, leaving only horizontal cosine components of E. )</em>
where  is the radius of curvature.
 is the radius of curvature. 
Now 
 ,
,
where  is the charge per unit length, and it has the value
 is the charge per unit length, and it has the value 

Thus, the electric field at the center of the curvature of the arc is: 


Now, we find  and
 and  . To do this we ask ourselves what fraction is the arc length  3.0 of the circumference of the circle:
. To do this we ask ourselves what fraction is the arc length  3.0 of the circumference of the circle: 

and this is  
 radians.
 radians.
Therefore, 

evaluating the integral, and putting in the numerical values  we get: 

