Answer:
A) Force
Explanation:
It is an example of force since force is a vector quantity so it has magnitude and direction. In this case the magnitude is equal to 5 [N] and the direction is upward.
The weight can not be, as it always acts downward.
Mass is not a force, its unit is given usually in kilogram [kg]
Is the velocity constant? Is there any friction?
3 meters per second
then after 40 seconds it must 3*40 = 120 meters
120 meters or 0.12 km if you will
Answer:
Bohr's greatest contribution to modern physics was the atomic model. ... Bohr was the first to discover that electrons travel in separate orbits around the nucleus and that the number of electrons in the outer orbit determines the properties of an element
Explanation:
Answer:
1) The greatest height attained by the ball equals 20.387 meters.
2) The time it takes for the ball to reach 15 meters approximately equals 1 second.
Explanation:
The greatest height will be attained when the ball stop's in the air and starts falling back to the earth.
thus using third equation of kinematics we obtain the height attained as

where
'v' is the final speed of the ball
'u' is the initial speed of the ball
'a' is the acceleration that the ball is under which in this case equals 9.81 
's' is the distance it covers
Thus for maximum height applying the values in the equation we get

Using the same equation we can find the speed of the ball when it reaches 15 meters of height as

the time it takes to reduce the velocity to this value can be found by first equation of kinematics as
