A grapefruit falls from a tree and hits the ground .75 seconds later. How far did the grapefruit drop? What was its speed?
1 answer:
1) The grapefruit is in free fall, so it moves by uniformly accelerated motion, with constant acceleration 
. Calling h its height at t=0, the height at time t is given by
We are told thatn when
the grapefruit hits the ground, so h(0.75 s)=0. If we substitute these data into the equation, we can find the initial height h of the grapefruit:
2) The speed of the grapefruit at time t is given by
where
is the initial speed of the grapefruit. Substituting t=0.75 s, we find the speed when the grapefruit hits the ground:
We are told thatn when
2) The speed of the grapefruit at time t is given by
where
You might be interested in
To solve this problem we will apply the linear motion kinematic equations. On these equations we will define the speed as the distance traveled in a space of time, and that speed will be in charge of indicating the reaction rate of the individual. In turn, using the ratio of speed, position and acceleration, we will clear the position and determine the distance necessary for braking.
The relation to express the velocity in terms of position for constant acceleration is as follows
Here,
u = Initial velocity
v= Final velocity
a = Acceleration
= Initial position
s = Final position
PART 1) Calculate the displacement within the reaction time
In this case we can calculate the shortest stopping distance
PART 2)
PART 1) Calculate the displacement within the reaction time
In this case we can calculate the shortest stopping distance
While a person without alcohol would cost 517ft to slow down, under alcoholic substances that distance would be 616ft