Answer:
option C
Explanation:
given,
Q = +3.2 x 10⁻¹⁹ C 
E = 5.0 X 10⁵ V/m
 B = 0.80 T
ion's acceleration is zero  
when acceleration is zero the magnitude of both the forces becomes equal.
q E = q V B
 v = 
 v= 
v = 6.25 × 10⁵ m/s ≈ 6.3 × 10⁵ m/s 
hence, the correct answer is option C
 
        
             
        
        
        
Sound waves or bounces off the wall and light waves are waves of light
        
             
        
        
        
Answer:
Mass remains constant but weight reduces
Explanation:
Mass is the amount of matter in an object so whether on moon or any other planet, it does not change despite the changes in acceleration. 
Weight is a product of mass and acceleration due to gravity, expressed as W=mg where m is the mass, W is weight and g is acceleration. From the above formula, it is evident that when you decrease g, then W also decreases while m is constant. Similarly, when m is constant and g is increased then W also increases.
Therefore, for this case, since g decreases, the weight decreases but mass remains constant.
 
        
             
        
        
        
Given
Three 7 ohm resistor are in series.
The battery is V=10V
To find
The equivalent resistance
Explanation
When the resistance are in series then the resistance are added to find its equivalent.
Thus the equivalent resistance is:

Conclusion 
The equivalent resistance is 21 ohm
 
        
             
        
        
        
Answer:
Multiply the air pressure by the area of the tabletop. 
Explanation:
The relationship between pressure, force and area is given by:

where in this case, p is the air pressure, F is the force exerted and A the area of the tabletop. By re-arranging the equation, we can solve for F, the force exerted:

So, the correct answer is:
The force exerted on the tabletop can be found by multiplying the air pressure by the area of the tabletop.