Answer:

Explanation:
The acceleration of the train is given by:

where:
u = 5 m/s is the initial velocity of the train
v = 45 m/s is the final velocity of the train
t = 8 s is the time taken for the train to increase the velocity
Substituting numbers into the formula, we find

Answer:
The length of the string is 0.051 meters
Explanation:
It is given that,
Tension in the string, T = 240 N
Mass of the string, m = 0.086 kg
Speed of the wave, v = 12 m/s
The speed of the wave on the string is given by :

M is the mass per unit length of the string i.e. M = m/l.......(1)
So, 

M = 1.67 kg/m
The length of the string can be calculated using equation (1) :


l = 0.051 m
So, the length of the string is 0.051 meters. Hence, this is the required solution.
It’s a feature of quantum-mechanical systems allowing a particle's time evolution to be arrested by measuring it frequently enough with respect to some chosen measurement setting.
Moving clouds. The doppler effect is specifically used to measure motion.
Answer:
Push and pull is the 3rd motion.