How can atoms make up all of the substances around you? Because there are a lot of atoms in the substances. ... If atoms are made of smaller parts such as electrons,why are atoms considered the basic unit of matter? It is the smallest unit that has the chemical property's of an element.
Answer:

Explanation:
Given


Required
Determine the speed of B w.r.t A
The question implies that, we determine the relative velocity of B w.r.t A
Because both trains are moving towards one another, the required velocity is a
both trains:
This is shown below:



Answer:
Scientific investigation is a quest to find the answer to a question using the scientific method. In turn, the scientific method is a systematic process that involves using measurable observations to formulate, test or modify a hypothesis.
Explanation:
Answer:
a) 
b) imagen adjunta
Explanation:
a) Primero debemos hacer la conversión de 81 km/h a m/s, esto es 22.5 m/s.
Ahora, usando la ecuacion cinemática, en un movimiento acelerado tenemos:

Queremos encontrar la posición hasta detenerse, osea vf = 0.



b) Para este caso el gráfico se encuentra adjunto.
Espero que te sirva de ayuda!
Answer:
1 m
Explanation:
L = 100 m
A = 1 mm^2 = 1 x 10^-6 m^2
Y = 1 x 10^11 N/m^2
F = 1000 N
Let the cable stretch be ΔL.
By the formula of Young's modulus



ΔL = 1 m
Thus, the cable stretches by 1 m.