Answer:
5) The approximate height is about 80 m. Choice (c)
6) The stone takes about 3 seconds to rise to its maximum height
Explanation:
Free Fall Motion
A free-falling object falls under the sole influence of gravity. Any object that is being acted upon only by the force of gravity is said to be in a state of free fall.
If an object is dropped from rest in a free-falling motion, it falls with a constant acceleration called the gravitational acceleration, which value is [tex]g = 9.8 m/s^2[/tex].
The distance traveled by a dropped object is:
[tex]\displaystyle y=\frac{gt^2}{2}[/tex]
Question 5
Given the stone reaches the ground in t=4 seconds, the height of the tower is:
[tex]\displaystyle y=\frac{9.8*4^2}{2}=78.4\ m[/tex]
The approximate height is about 80 m. Choice (c)
Question 6
Vertical Motion
The vertical motion of an object is controlled by the force of gravity. This means that there is a non-zero net force acting on the object that makes it accelerate downwards.
If the object is thrown upwards at speed vo, its speed at time t is:
[tex]v_f=v_o-g.t[/tex]
The stone reaches its maximum height when the final speed is zero, thus:
[tex]v_o-g.t=0[/tex]
Solving for t:
[tex]\displaystyle t=\frac{v_o}{g}[/tex]
The stone is thrown vertically upwards with vo=30 m/s, thus:
[tex]\displaystyle t=\frac{30}{9.8}[/tex]
[tex]t=3.06\ s[/tex]
[tex]t\approx 3\ s[/tex]
The stone takes about 3 seconds to rise to its maximum height
