Answer:
The amount of current that must flow through the wire for it to be suspended against gravity by magnetic force = 6.125 A
Explanation:
Force on a wire carrying current in an electric field is given by
F = (B)(I)(L) sin θ
For this question,
The magnetic force must match the weight of the wire.
F = mg
mg = (B)(I)(L) sin θ
(m/L)g = (B)(I) sin θ
Mass per unit length = 75 g/m = 0.075 kg/m
B = magnetic field = 0.12 T
I = ?
g = acceleration due to gravity = 9.8 m/s
θ = angle between wire's current direction and magnetic field = 90°
0.075 × 9.8 = 0.12 × I sin 90°
I = 0.075 × 9.8/0.12 = 6.125 A
 
        
             
        
        
        
Answer:
21.21 m/s
Explanation:
Let KE₁ represent the initial kinetic energy.
Let v₁ represent the initial velocity. 
Let KE₂ represent the final kinetic energy. 
Let v₂ represent the final velocity.
Next, the data obtained from the question:
Initial velocity (v₁) = 15 m/s
Initial kinetic Energy (KE₁) = E
Final final energy (KE₂) = double the initial kinetic energy = 2E
Final velocity (v₂) =? 
Thus, the velocity (v₂) with which the car we travel in order to double it's kinetic energy can be obtained as follow:
KE = ½mv²
NOTE: Mass (m) = constant (since we are considering the same car) 
KE₁/v₁² = KE₂/v₂²
E /15² = 2E/v₂²
E/225 = 2E/v₂²
Cross multiply 
E × v₂² = 225 × 2E
E × v₂² = 450E
Divide both side by E
v₂² = 450E /E
v₂² = 450
Take the square root of both side. 
v₂ = √450
v₂ = 21.21 m/s
Therefore, the car will travel at 21.21 m/s in order to double it's kinetic energy. 
 
        
             
        
        
        
Answer:
• 36.4 kg of coal.
• 80 pounds of coal.
Explanation:
Using proportionality constant, 
Mass of coal = 1,000,000/27,500,000 btus/metric ton
= 0.0364 metric tons of coal
Mass of coal = 1,000,000/25,000,000 btus/ton
= 0.04 tons of coal.
Converting metric tons to kilogram, 
1 metric ton = 1000kg,
0.0364 metric ton;
= 36.4 kg of coal.
Converting tons to pounds, 
1 ton = 2000 pounds,
0.04 metric ton;
= 80 pounds of coal.
 
        
             
        
        
        
Answer: ask other people if they like it, or ask what they want to add
Explanation: because maybe other people can can help him improve and brainstorm with other’s. 
 
        
                    
             
        
        
        
Answer:
I believe the answer is D.
Explanation:
Protons are found inside the nucleus so are neutrons. Electrons are found outside the nucleus.