Physics 100 Due 11/6-Fall 2017 Homework 24 You must show all work to receive cre
ID: 1775013 • Letter: P
Question
Physics 100 Due 11/6-Fall 2017 Homework 24 You must show all work to receive credit. Write in a clear and organized manner, unclear work will not receive credit. 1 Warm-up Questions a) The reason we use two different notations for the magnitude of a vector is that sometimes the the mean- ings can be a little ambiguous. Consider an initial position of (3 m)i, and a final position of ry =(4 m)j. Compute -ry-ri, and Ian = ry-ri . Which one is the magnitude of the displace- ment? Magnitude of Displacement b) An object, initially on the ground, is launched vertically straight up into the air. The object goes up and comes back down, landing back at the same spot in started from exactly 4.0 seconds after it was launched. Assuming air resistance was negligible, what was the object's initial velocity? Initial Velocity:Explanation / Answer
a)
ri = (3m)I, rj = (4m)j
r = (4m)j - (3m)I = 1m
Magnitude of displacement = |r| = |(4m)j - (3m)I|
|r|= 1m
b)
Time needed to go maximum height = 4.0s/2 = 2.0s
Acceleration due to gravity =9.80m/s^2
Velocity at maximum height = vf=0m/s
Use kinematic eqn,
vf=vi+at
vf=vi-gt
Plugging values,
0 = vi – 9.8*2.0
vi= 19.6 m/s