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:
13 km/h
Explanation:
Average speed = distance/time
Let the total distance and total time taken for the whole trip be d km and t hours respectively
Average speed for the whole trip = 82 km/h
d = 82t
The distance covered in the first half = d1/2
Time taken = t/2
Average speed = 69 km/h
69 = d1/2 ÷ t/2
d1 = 69t
The distance covered in the second half = d2/2
Time taken = t/2
Let the average sly for the see half be A
A = d2/2 ÷ t/2
d2 = At
d = d1 + d2
82t = 69t + At
At = 82t - 69t
At = 13t
A = 13t/t = 13 km/h
Answer: Radiation
Explanation:
There are three ways in which the thermal transfer occurs:
1. By Conduction, when the transmission is by the <u>direct contact</u>.
2. By Convection, heat transfer <u>in fluids </u>(like water or the air, for example).
3. By Radiation, by the <u>electromagnetic waves</u> (they can travel through any medium and in <u>vacumm</u>)
So, in the outter space is vacuum, this means the energy cannot be transmitted by convection, nor conduction. It must be transmitted by electromagnetic waves that are able to travel with or without a medium, and this is called radiation.
Playing catch involves the ball moving in one direction in the air when you exert force. When the ball is in air, there is a gravitational force and a little it of backward air resistance until the other person catches it.
Answer: 7.5 rev/s
Explanation:
We are given the angular velocity
a helicopter's main rotor blades:

However, we are asked to express this
in the International Systrm (SI) units. In this sense, the SI unit for time is second (
):

