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physics projectiles

### Transcript of Projectiles Review Ak

• Student A. \L '/ Honors Physics Date _

PROJECTll..ES REVIEW

1. An eagle is flying due east at 8.9 mls carrying a gopher in its talons. The gophermanages to break free at a height of 12 m. What is the magnitude of the gopher's.velocity as it reaches the ground? Note: effects of air resistance are not included in this

Vi)t::: g.q ~'r calculation.Vj.(O

v -=- V (g.q ....,\$)1. +- 2}5 .If'i w.. 'LIs>'"G'= '~~/S)

2. A physics student standing on the edge of a cliff throws a stone vertically downwardwith an initial speed of 10.0 mls. The instant before the stone hits the ground below, itis traveling at a speed of30.0 mls. If the physics student were to throw the rockhorizontally outward from the cliff instead; with the same initial speed of 10.0 mis, whatis the magnitude of the velocity of the stone just before it hits the ground?

3. A tennis ball is thrown from ground level with velocity ve directed 300 above thehorizontal. If it takes the ball 0.5 s to reach the top of its trajectory, what is themagnitude of the initial velocity?

- ~ - ~-//-- I

Yo /,/

V\''1 + 0..'( -!:"'P

i.2- _ Gt.81~ (O.~ S )2... ~l.--~~~------~--------~~

foX0=

A

Page 1

• Use the following to answer questions 4-5: /

A projectile is fired at an angle of 55.0 above the horizontal with an initial speed of35.0 mls.

Vi..,.-= v" cose -== 35 ~ (oS5So '::: 20. I ""')5 .--------V;'1 = V,.5lVte z: 35 ~ \$tV\55:::: 28.7...,/;s

4. What is the magnitude of the horizontal component ofthe projectile's displacement atthe end of 2 s?

d - \J' 1: -= (20. I~ ) (2 s = ~o.2 Ih ~ ~X - \X.> C/

5. How long does it take the projectile to reach the highest point in its trajectory?'\... 1..

V {-'t -=:. Vi'f + Z ~'1 l>'(O'L= (Zg:7 .....'5)~ +- '2..( -Q.81 ~ )Py

6. A projectile is fired horizontally with an initial speed of 57 mls. What are the horizontaland vertical components of its displacement 3.0 s after it is fired?horizontal vertical I/O

t! \..) ./1. ( i: 1..d)(~ \}~X' t cA't -:: Vl (..+ Z ~l

( I l..==- 51.!!. ~.oS J r ( .~ 01 W\ ) '3 OS)5 0'1 -::: 2: -,'0 ~ \. .~r~'o"")

Page 2

• 7. A spring-loaded gun is aimed horizontally and is used to launch identical balls withdifferent initial speeds. The gun is at a fixed position above the floor. The balls arefired one at a time. .

If the speed of the second ball fired is twice the speed of the first ball fired, how is thehorizontal range (denoted R in the figure) affected?

t>x ::: V \ >(' t,r~ .t"'~ ~O'fl 'lo~~ClI >fe~J dol,{ kle S I ~e ~\'\.ge \).x (Oy (2.)\N \ \ \ do'-\ b\e a> wei t.

Use the following to answer questions 8-10:

A shell is fired with a horizontal velocity in the positive x direction from the top of an SO-m highcliff The shell strikes the ground 1330 m from the base of the cliff. The drawing is not to scale.

n- ...-'..."',80m " ,

\,\

\)~""V/t ....lll~i~( ~)it..-go~ == Z(-~ gl ~

[+~~.~>S. Determine the initial speed of the shell. .

V'x ~ 329. '2. MIS

~EMI0Page 3

• : 100:0o'(t,

9. What is the magnitude of the velocity of the shell as it hits the ground? (~a ro\.\~~ ') "1\1'1 -: Vi'1 + ~'1t V:: VVx'\. i- V,# t,

=-0 +(_q.~I~)(~.ot(S) . r"'---'\.-(---",~~. \$ -::::y('300~)+ -3q.{;>~)- - ~'tb3 'MIS. . . C.)~- ~ 302,., b ~15 ':::: '3>00 ~/> _ ( \ S\~ "\"V

1O. What is the magnitude of the acceleration of the shell just before it strikes the ground?

Gv co - 'l.~1 ""~yUse the following to answer questions 11-12:

A rock is kicked horizontally at a speed of 16 mls from the edge of a cliff. The rock strikes theground 65m from the foot of the cliff of height H as suggested in the figure, which is not drawnto scale. Neglect air resistance.

16m1s~- ....11--

~1'_------65m------~~~1

11. How long is the rock in the air? 65""If,'NtIS

Page 4

• 12. What is the approximate value of H, the height of the cliff?o.:'" '2 I 1.d~-= Vi\.,+ z Oiyi . = 2. tA1t

...l.,_ l. (_'to e I~ ) (4./ ~)"'L:::= - 'l?L.4 5M\14,_ z: 5"-

13. A ball is fired at an angle of 45, the angle that yields the maximum range in the absenceof air resistance. What is the ratio of the ball's maximum height to its range?

'1.

"f'1"'- ~ V~'t + 1..tA~'0'1

o = \j\~ - 20 t>'( 2..0.L Vl'fL...4f-:=:'

10

2. 'V\'fl>x~ \llX - --\0 ?

VI-t'lV l'f 5" 0 ~illtAt 'Z-O j_ +a.~45- -._- - - - 4-

\{ .\)/, Vi)