Please guys!! Open-Response Homework Problem 4.4 You are on a scouting mission o
ID: 2283315 • Letter: P
Question
Please guys!!Open-Response Homework Problem 4.4 You are on a scouting mission on an Earth-like planet (which happens to have a local gravitational acceleration with magnitude g) in a distant solar system. Toward the end of the day you tind yourself at the top of a 1000ft cliff above your camp. Being an adventurous soul, you decide that rather than walking all the way around, you will just use your jet-pack to get down. So you jump off the cliff. Your Erusty jet-pack fails to ignite immediately, however, so you have to connect the backup ignition mechanism. After free-falling for 5 seconds, you manage to ignite your jet-pack, suddenly (and rather drastically) changing your acceleration, which thereafter remains constant. You reach the ground 7 seconds after igniting the jet-pack. (a)|2 pt(s)JHow far do you fall before you ignite the jet-pack? b)2 pt(s)JWhat is your velocity when you ignite the jet-pack? c)/2 pt(s)What is your acceleration after you ignite the jet-pack? d)[2 pt(s)JAt what speed do you hit the ground? Open-Response Homework Problem 4.5 You are watching T.V. one day and find a channel about boxing. The show analyzes the velocity of a forward jab punch. The graph below shows the velocity of the fist as a function of time throughout the motion of the punch. Assume that the punch starts with the fist at the shoulder, and the fist moves directly forward until the arm is extended its full length, straight out. (a)[7 pt(s) Given the motion described by the velocity-time graph at the end of the problem, how long is the person's arm? (Hint: this would be the distance, travelled by the fist.) What is the average acceleration for the entire extension of the arm/fist? Justify your (b)[4 pt(s) (c)[13 pt(s) (d)[8 pt(s)Draw the position vs. time graph, assuming that the initial position of the fist is zero answer! Draw the a-t graph for the motion of the fist on the graph given right after the graph of the motion.
Explanation / Answer
4.4
A) 1000ft = 304m
You free fall for 5 seconds
x0 = initial displacement = 0m
v0 = initial velocity = 0m/s
g = gravitation constant = 9.8m/s^2
x = v0t + 1/2 at^2 + x0
x = 0 + 1/2(9.8 m/s^2)(5^2) + 0
x = 122.5m
B) v = v0 + at
v = (9.8m/s^2)(5sec) = 49m/s
C) Once you ignite your jetback, the accerleration stablizes and takes 7 seconds to arrive to ground after that.
x = 304m - 122.5m once ignited so 181.5m left to hit the ground
x = v0*t + 1/2 at^2 + x0
181.5m = 0 + 1/2 * a * (7^2) +0
181.5*2/49 = a
a = 7.4 m/s^2
D) v = v0 + at
v = 0 + (7.4m/s^2)*7 = 51.8m/s
4.5
a) Picking a random velocity, when V = 4m/s, t= .05sec
V = V0 +at ---> 4m/s = 0 + a(.05) ---> a = 80 m/s^2
x = V0 +1/2 at^2 + x0
x = 0 + 1/2 (80m/s^2)(.05^2) = .1m long is the length of his arm
b) x= .1m when v = 0, t = .14sec
x = v0 + 1/2 at^2 + x0
.1m = 1/2 a(.14^2) ---> a = (.1m)(2)/(.14sec)^2 = 10.20m/s^2
C and D) Graphs can be drawn above by using the numbers I have found.