What is measurement

A stone is dropped from the upper observation deck of a tower, 750 m above the ground. (assume g = 9.8 m/s2.) (a) find the dista

Gekata [30.6K]

(a) The stone moves by uniform accelerated motion, with constant acceleration $g=9.81 m/s^2$ directed downwards, and its initial vertical position at time t=0 is 750 m. So, the vertical position (in meters) at any time t can be written as
$y(t)= y_0 - \frac{1}{2}gt^2= 750 - 4.9 t^2$

(b) The time the stone takes to reach the ground is the time at which the vertical position of the stone becomes zero: y(t)=0. So, we can write
$750-4.9 t^2 = 0$
from which we find the time t after which the stone reaches the ground:
$t= \sqrt{\frac{750 m}{4.9 m/s^2 }}= 12.37 s$

(c) The velocity of the stone at time t can be written as
$v(t) = -gt$
because it is an accelerated motion with initial speed zero. Substituting t=12.37 s, we find the final velocity of the stone:
$v(12.37 s)=-(9.81 m/s^2)(12.37 s)=-121.3 m/s$

(d) if the stone has an initial velocity of $v_0 = 6 m/s$ , then its law of motion would be
$y(t)=y_0 - v_0t - \frac{1}{2}gt^2$
and we can find the time it needs to reach the ground by requiring again y(t)=0:
$0=750 - 6t - 4.9 t^2$
which has two solutions: one is negative so we neglect it, while the second one is t=11.78 s, so this is the time after which the stone reaches the ground.

5 0

3 years ago

What changes a ball velocity

Grace [21]

Answer/Explanation: Speed and direction can change with time. When you throw a ball into the air, it leaves your hand at a certain speed. As the ball rises, it slows down. Then, as the ball falls back toward the ground, it speeds up again. When the ball hits the ground, its direction of motion changes and it bounces back up into the air.

5 0

4 years ago

Light and sound waves both share what characteristic?

Phoenix [80]

Answer: (Light and sound both require a medium in which to travel)

Explanation: Sound and light always have the means to travel and get somewhere as fast as possible. Light is always faster than sound but it does not matter because they both almost always get where they want.

Part 2. light was composed of particles or waves, a wave-particle dual nature soon was found to be characteristic of electrons as well. The evidence for the description of light as waves was well established at the turn of the century when the photoelectric effect introduced firm evidence of a particle nature as well. basically when light hits a metal object . :)