Explanation:
First, we need to determine the distance traveled by the car in the first 30 minutes,  .
.
Notice that the unit measurement for speed, in this case, is km/hr. Thus, a unit conversion of from minutes into hours is required before proceeding with the calculation, as shown below
                                           
Now, it is known that the car traveled 40 km for the first 30 minutes. Hence, the remaining distance,  , in which the driver reduces the speed to 40km/hr is
 , in which the driver reduces the speed to 40km/hr is
                                               .
.
Subsequently, we would also like to know the time taken for the car to reach its destination, denoted by   .
.
                                                .
.
Finally, with all the required values at hand, the average speed of the car for the entire trip is calculated as the ratio of the change in distance over the change in time.
                                                      
Therefore, the average speed of the car is 50 km/hr.
 
        
             
        
        
        
One form of Ohm's Law says . . . . . Resistance = Voltage / Current .
R = V / I
R = (12 v) / (0.025 A)
R = (12 / 0.025) (V/I)
<em>R = 480 Ohms</em>
I don't know if the current in the bulb is steady, because I don't know what a car's "accumulator" is.  (Floogle isn't sure either.)
If you're referring to the car's battery, then the current is quite steady, because the battery is a purely DC storage container.
If you're referring to the car's "alternator" ... the thing that generates electrical energy in a car to keep the battery charged ... then the current is pulsating DC, because that's the form of the alternator's output.  
 
        
             
        
        
        
There are two particular cases, the first is when Object A is attracted to the neutral wall. This would indicate that the object is not neutral, as there is an attraction.
At the same time we know that Object A is attracted to an object B. And therefore, the load of A must be opposite to that of B. Remember that opposite charges attract each other. If the charge of object B is positive, then the charge of object A will be negative.
Option B is correct: It has a negative charge.
 
        
             
        
        
        
Momentum = mass x velocity 
12 = 4 x v | ÷ both sides by 4
12 ÷ 4 =v
v= 3 m/s