A ball of mass 8 kg falls from rest from a height of 100 m. Neglecting air resistance,calculate its kinetic energy after falling
2 answers:
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(a) At level A Potential Energy is 2940 J.
(b) At level B Potential Energy is 1960 J.
(c) At level C Potential energy is 1470 J.
(d) At level D Potential energy is 0 J.
(e) The change in Potential energy if the object moves from A to B is 980 J.
<u>Explanation</u>:
Given that,
Mass of an object is 5 kg (m) at a height of 60 m (h) above the ground as shown in the given figure.
Potential energy of an object is calculated by using the formula m × g × h. “g” is acceleration due to gravity on earth is 9.8 .
(a) At level A:
At height (h) is 60 m above ground.
Potential energy = 5 × 9.8 × 60
Potential energy = 2940 J
(b) At level B:
At height (h) is 40 m above ground.
Potential energy = 5 × 9.8 × 40
Potential energy = 1960 J
(c) At level C:
At height (h) is 30 m above ground.
Potential energy = 5 × 9.8 × 30
Potential energy = 1470 J
(d) At level D:
At height (h) is 0 m above ground (object is on the ground).
Potential energy = 5 × 9.8 × 0
Potential energy = 0 J
(e) Change in “Potential energy” when it moves from “A” to “B”
Change in “Potential energy” in difference in initial “Potential energy” (at level A) and final “Potential energy” (at level B)
= 2940 - 1960
= 980 J
Therefore, change in “Potential energy” is 980 J.
A) Both players are moving by uniformly accelerated motion, and we can write the position at time t of each of the two players as follows:
where
is the acceleration of the first player
is the acceleration of the second player
is the initial distance between the two players
and where I put a negative sign in front of the acceleration of the second player, since he's moving in the opposite direction of the first player.
The time t at which the two players collide is the time t at which
, therefore:
from whic we find
b) We can use the equation of
to find how far the first player run in t=8.5 s:
where
and where I put a negative sign in front of the acceleration of the second player, since he's moving in the opposite direction of the first player.
The time t at which the two players collide is the time t at which
from whic we find
b) We can use the equation of
Explanation:
use the diagram^
horizontal velocity of the object nvr changes, it'll stay 50m/s till it hits the ground
initial vertical velocity = 0
to find the final vertical velocity, use the formula:
where u = 0m/s, a = 9.8m/s², and s = 2000m
solve for v.
for time taken to reach ground, use the formula:
where v = the value for v u calculated above, u = 0 m/s, a = 9.8m/s² and solve for t.
