Answer:
29.4 uN
Explanation:
The electric force between two charges can be calculated using Coulomb's Law. According to this law the force between two point charges is given as:
where k is a proportionality constant known as the Coulomb's law constant. Its value is 
Nm²/C²
r = distance between charges = 70 cm = 0.7 m
q1 = q2 = 4nC = 
C
The negative sign indicates that the charges are negative. In the formula we will only use the magnitude of the charges.
Using these values in the formula, we get:
Therefore, the magnitude of repulsive force between the given charges will be 29.4 uN
Typical examples of inelastic collision are between cars, airlines, trains, etc.
For instance, when two trains collide, the kinetic energy of each train is transformed into heat, which explains why, most of the times, there is a fire after a collision. However, the momentum of the two trains that are involved in the collision remains unaffected. So, the trains collide with all their speed, maintaining their momentum, yet their kinetic energy is transformed into heat energy.
Another way to explain a train or a car collision is this: when the two trains or cars collide, they stick together while slowing down. They slow down because their kinetic energy is gradually lost. Still, they collide because they conserve their momentum.
False. because the object cannot freefall due to resistance, so it cannot develop full acceleration.
The appropriate response is Zero degrees. The beam will leave the two mirrors along a way parallel to the one it came in on. This is the guideline of the corner reflector, which is frequently utilized as a radar target. Take note of that the corner reflector utilizes three reflecting surfaces (that are set up at 90o from each other) rather than the two like are being utilized here. Wikipedia has a truly awesome drawing that shows this two-dimentional issue pleasantly. A moment connection is given to the article on the corner reflector and the 3-D angles.
