Question

??

Answer 1

21sin(51)
21cos(51)

Answer 2

for a and b

Answer 3

good (remember that cos is the horizontal velocity so that must be a)

Answer 4

(you need to switch them)

Answer 5

a. What is the horizontal component of the velocity? (2 points)

21cos(51)=13.22

b. What is the vertical component of the velocity? (2 points)

21sin(51)=16.32

Answer 6

good

for c) use kinematics equation 1 to find the time

Answer 7

* I would recommend writing this down somewhere: at the peak of a parabolic projection the velocity in the y-direction is 0

Answer 8

okay will do

Answer 9

with that in mind, try solving for time

Answer 10

vf = vi + at, plug everything except t in and solve for time

Answer 11

Sorry a little busy,

Answer 12

okay let me plug in the numbers

Answer 13

vf = vi + at
0=16.32+(9.8)t

Answer 14

16.32=0+(9.8)t

Answer 15

you had it right the first time

0=16.32+(9.8)t

since the final state is at the top of the parabola, vf is 0 and vi is the initial velocity given in the problem

Answer 16

-1.67

Answer 17

yeah good (if we change 9.8 to -9.8 we should get the positive time value, 1.67 seconds)

Answer 18

for d) use deltax = v_0 * t + (1/2)at^2 to find height

Answer 19

so it would be positive ?

Answer 20

yeah (time can't be negative)

Answer 21

oh yeah lol

Answer 22

okay so d

Answer 23

\(\color{#0cbb34}{\text{Originally Posted by}}\) @Vocaloid
for d) use deltax = v_0 * t + (1/2)at^2 to find height
\(\color{#0cbb34}{\text{End of Quote}}\)

Answer 24

okay so deltax=0*t+ (1/2)at^2

Answer 25

@Vocaloid

Answer 26

the initial velocity is not 0 (it's equal to the initial vertical component of velocity)

you must also substitute the time value for c) and -g for acceleration

Answer 27

16.32*1.67+(1/2)(-9.8)t^2

Answer 28

you also need to substitute for the other t

Answer 29

16.32*1.67+(1/2)(-9.8)1.67^2

Answer 30

13.59

Answer 31

good

for e) the total time is just double the time it took to reach the top

so double the answer from c)

Answer 32

1.67*2=3.34 seconds

Answer 33

good

for f) the velocity in the x-direction is constant so multiply the x-direction velocity * total time to get distance

Answer 34

13.22*3.34=44.15 m/s

Answer 35

the units of distance are not m/s

if you are confused about units there are two ways to clear it up:

1. the units must cancel out

m/s * s --> the s cancels out so it is m

2. thinking about what the physical quantity we are looking for is

distance is m

Answer 36

okay so distance is m
velocity is m/s
and time is s

Answer 37

yes

Answer 38

what is m/s/s again?

Answer 39

acceleration

Answer 40

so for height it would be?

Answer 41

m

Answer 42

OKay thanks !!