The speed of light is , but it still takes time for light to get to its destination. this is not usually a noticeable effect over short distances here on the earth, but as objects get farther away, the "lag time" for information becomes more . we see objects not as , but rather we see them as . for farther objects, this "lookback time" becomes . since extremely distant objects will also look incredibly to us, we need very large telescopes, which can gather and focus enough light to observe such objects.

so easy. just google the electromagnetic waves and it’ll pop up.

force is based upon mass and acceleration.the statement is not always true.

it can be explained from newton's second law of motion.

as per newton's second law of motion the rate of change of momentum is directly proportional to the applied force and takes place along the direction of force.

mathematically it can be written as -

                                              ⇒      

here   k is the proportionality constant whose value is 1.

                                                            [a is the acceleration=dv/dt]

hence we see that force not only depends on mass and acceleration but also on velocity and rate of change of mass. force f will depend on mass and acceleration only when mass is constant.

hence the statement that force is based upon mass and acceleration is false.