Answer: A
Hope this help you!!
Answer:
Time = 6 years
Explanation:
First, we will calculate the no. of half life periods required to reduce the mass of Protactinium to the given value:
where,
n = no. of half-life periods = ?
m = initial mass = 86.3 g
m' = remaining mass = 10.8 g
Therefore,
Since the bases are the same. Therefore equating powers:
n = 3
Now we calculate the time:
<u>Time = 6 years</u>
Answer:
Material medium
compressions and rarefactions
Explanation:
A sound wave is an example of a mechanical wave. All mechanical waves require a material medium for propagation. The medium for the propagation of sound is air. This is the reason why, if you cover your mouth, it will be difficult for another person to hear whatever you are saying.
Sound is also a longitudinal wave. Longitudinal waves are described in terms of compressions and rarefactions. Compressions refer to areas where air molecules crowd together while rarefactions refer to areas where the air molecules spread out.
Answer:
44.3 m/s
Explanation:
Given that a ball is thrown horizontally from the top of a building 100m high. The ball strikes the ground at a point 120 m horizontally away from and below the point of release.
What is the magnitude of its velocity just before it strikes the ground ?
The parameters given are:
Height H = 100m
Since the ball is thrown from a top of a building, initial velocity U = 0
Let g = 9.8m/s^2
Using third equation of motion
V^2 = U^2 + 2gH
Substitute all the parameters into the formula
V^2 = 2 × 9.8 × 100
V^2 = 200 × 9.8
V^2 = 1960
V = 44.27 m/s
Therefore, the magnitude of its velocity just before it strikes the ground is 44.3 m/s approximately
Answer:
The polarity of the magnetic field changes
Explanation:
This because The magnetic field generated is always perpendicular to the direction of the current and parallel to the solonoid. Hence if we reverse the current the direction of magnetism also reverses. In other words the magnetic poles gets reversed (North pole becomes south pole and the south pole becomes the north pole)
