Answer:
d.Net force
Explanation:
The net force is the force which is the sum of all the forces acting on an object simultaneously.
Answer:
Answer to the question:
Explanation:
A black hole is a finite region of space within which there is a mass concentration high and dense enough to generate a gravitational field such that no material particle, not even light, can escape it.
Answer:
B. False
The true statement will be:
After three half-lives, one-eighth of an original radioactive parent isotope remains, and seven-eighth has decayed into daughter isotopes.
Explanation:
Half life means the time after which the amount of the given substance becomes half of its initial amount, by radiation.
Thus after each successive half life the material is halved or half of it is decayed, which leads to a general formula:
Remaining Amount = 1/2^n of parent isotope
where, n is the number of half lives passed. So, for three half-lives:
Remaining Amount = 1/2^3 of parent isotope
<u>Remaining Amount = 1/8 of parent isotope</u>
Thus, the decayed amount will be:
Decayed Amount = (1-1/8) of parent isotope
<u>Decayed Amount = 7/8 of parent isotope</u>
Thus, the given statement is <u>B.False</u>
Answer:
b friction
Explanation:
Contact forces
Contact forces are forces that act between two objects that are physically touching each other. Examples of contact forces include:
Reaction force
An object at rest on a surface experiences reaction force. For example, a book on a table.
A box rests on a table. There are two arrows, equal in size but going in opposite directions, up and down, from the point where the box meets the table.
Tension
An object that is being stretched experiences a tension force. For example, a cable holding a ceiling lamp.
A box hangs from a rope. Two arrows which are equal in size act upwards and dowards from the top and bottom of the rope.
Friction
Two objects sliding past each other experience friction forces. For example, a box sliding down a slope.
A box rests on an incline. There are three arrows; one acting vertically downwards from the centre of the box’s base. One arrow acts perpendicular to the incline. One arrow acts up the incline.
Air resistance
An object moving through the air experiences air resistance. For example, a skydiver falling through the air.
A box falls from the sky. Two arrows, equal in size and opposite in direction act upwards from the box and downwards from the box
When a contact force acts between two objects, both objects experience the same size force, but in opposite directions. This is Newton's Third Law of Motion.
