At the ground the ball will always have velocity along the direction of gravity. If upward motion is taken positive it will always have negative velocity at the ground because, if the ball was given an initial upward velocity then gravity will decelerate it and bring it down with a negative final velocity. If the ball is given an initial downward velocity then the ball will be further accelerated by gravity in the downward direction only, again maintaining negative direction. The magnitude however in both cases will be different. the final velocity at the ground will have higher magnitude in case of elevator moving downwards.
Answer:
B, C and D are true.
<h3>Explanation:</h3>
A is false because they appear a pale reddish colour not purple.
Answer:
Force and displacement.
Explanation:
Work done is positive when we push table and it move in the direction of applied force.
Answer:
4500 J
Explanation:
First, let's define some equations and derivations.
Our potential energy formula is:
Where <em>m </em>is mass (in kg), <em>g</em> is the gravitational constant (in m/s²), and <em>h</em> is height (in m).
We also know that <em>mg</em> is equal to the weight of an object (in N), from Newton's 2nd Law of Motion: F = ma (Force is equal to [constant] mass times acceleration).
Therefore, we can simply substitute force into the equation:
Where <em>F</em> is the force (in N) and <em>h</em> is still height (in m).
Now we can calculate the amount of potential energy in our system, measured in joules.
Substitute in the given variables, F = 500 N and h = 9 m:
Using simple Pre-Algebra rules, we find that:
This tells us that the we have 4500 joules of potential energy when I am 9 meters above the water on the edge of the diving board.
Answer:
The force becomes 16 times what it is now.
Explanation:
The formula for gravitational force is
F = G * m1 * m2 / r^2
When you do what you have described, you are setting a stage that not even the USS Enterprise (Star Trek) can get out of. The increase is huge.
If you double m1 and m2 and don't do anything to r, you've already increased the force by 4 times. (2m1 * 2m2 = 4 * m1 * m2)
But you are not finished. If you 1/2 the distance, you are again increasing the Force by 4 times. 1 / (2r) ^2 = 1/ 4* r^2
Because this is in the denominator, the 1/4 is going to flip to the numerator.
So the total increase is going to be 4 * (4 * m1 * m2) = 16 * m1 * m2.
Think about what that means. If you were out golfing, your drives would be roughly 1/16 times as far as they are now. Also you would be lugging around 16 times your weight around the golf course. My feeling is that you would never finish 5 holes at that rate.
