Answer:
The average velocity is 50 km/h south
Explanation:
The average velocity of an object is its total displacement divided by
the total time taken.
That means it is the rate at which an object changes its position from
one place to another.
Average velocity is a vector quantity.
The SI unit is meters per second.
A bicycle that starts 100 km south and is 120 km south of town after
0.4 hour.
The displacement = 120 - 100 = 20 km south
The time = 0.4 hour
The average velocity = 
, where D is the displacement
and t is the time
The average velocity of the bicycle = 
km/h
<em>The average velocity is 50 km/h south</em>
If you want it in meter per second, change the kilometer to meter
and change the hour to seconds
1 km = 1000 m
1 hour = 60 × 60 = 3600 seconds
The average velocity of the bicycle = 
m/s south
Answer:
0.03 A
Explanation:
From the question given above, the following data were obtained:
Voltage (V) = 12 V
Resistor (R) = 470 Ω
Current (I) =?
From ohm's law, the voltage, current and resistor are related by the following formula:
Voltage = current × resistor
V = IR
With the above formula, we can obtain the current in the circuit as follow:
Voltage (V) = 12 V
Resistor (R) = 470 Ω
Current (I) =?
V = IR
12 = I × 470
Divide both side by 470
I = 12 / 470
I = 0.03 A
Thus, the current in the circuit is 0.03 A
The main advantage of an electromagnet over a permanent magnet is that the magnetic field can be quickly changed by controlling the amount of electric current in the winding. However, unlike a permanent magnet that needs no power, an electromagnet requires a continuous supply of current to maintain the magnetic field.
Answer:
Option D
Explanation:
The work done can be given by the mechanical energy used to do work, i.e., Kinetic energy and potential energy provided to do the work.
In all the cases, except option D, the energy provided to do the useful work is not zero and hence work done is not zero.
In option D, the box is being pulled with constant velocity, making the acceleration zero and thus Kinetic energy of the system is zero. Hence work done in this case is zero.
