a) 2.75 s
The vertical position of the ball at time t is given by the equation
where
h = 4 m is the initial height of the ball
u = 12 m/s is the initial velocity of the ball (upward)
g = 9.8 m/s^2 is the acceleration of gravity (downward)
We can find the time t at which the ball reaches the ground by substituting y=0 into the equation:
This is a second-order equation. By solving it for t, we find:
t = -0.30 s
t = 2.75 s
The first solution is negative, so we discard it; the second solution, t = 2.75 s, is the one we are looking for.
b) -15.0 m/s (downward)
The final velocity of the ball can be calculated by using the equation:
where
u = 12 m/s is the initial (upward) velocity
g = 9.8 m/s^2 is the acceleration of gravity (downward)
t is the time
By subsisuting t = 2.75 s, we find the velocity of the ball as it reaches the ground:
And the negative sign means the direction is downward.
20/9.8 = 2.0 seconds. The ball stops after 2 seconds.
True : yes there are planets in the universe without a parent star called
rogue planets.
False : most stars are not binary
What is rogue planets ?
planets which do not orbits the planetary system is known as roque planets. For example, pluto. Rogue planets can be smaller and bigger than jupiter too.
Free-floating planets or rogue planets without orbits around stars may also harbor life, some scientists believe. Due to the gravitational effects of giant planets within their system, these planets get kicked out of their system like any other planets formed around stars.
no most stars are not binary, binary which means two stars orbit around the common center and approximately only 40 binary stars have been found till not in our solar system.
Read more about solar system at:
brainly.com/question/12075871
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This can be seen as a trick question because heat engines can typically never be 100 percent efficient. This is due to the presence of inefficiencies such as friction and heat loss to the environment. Even the best heat engines can only go up to around 50% efficiency.
