Answer:
Electrostatics is a branch of physics that studies electric charges at rest. Since classical physics, it has been known that some materials, such as amber, attract lightweight particles after rubbing. The Greek word for amber, or electron, was thus the source of the word 'electricity'.
Answer:
3
Explanation:
The half-life of a radioactive isotope is the time it takes for the mass of the sample to halve.
This can be rewritten as follows:

where
m(t) is the mass of the sample at time t
m0 is the original mass of the sample
n is the number of half-lives that passed
We see that if we take n=3, the amount of original sample left is

So 3 (3 half-lives) is the correct answer.
Answer:
Take the measurement of the distance (d) with a meter rule (in meters) and also measure the time (t) of the travel in seconds with a stopwatch.
question: What is the speed of the cart?
Explanation:
The speed of an object in motion is the distance covered by the object with respect to time, that is, the ratio of distance covered to the time taken to reach that distance.
Speed = distance / time
= d (in meters m) / t (in seconds s) = m/s