Unit 4 - Forces and Newton's laws Review Guide
1. Earth's gravity pulls a skydiver toward Earth. If this is the action force, what is the reaction force?
11- f kytvu '5
PI,I,I(".fI'lLb:.rf'~ -/oJ h;1".
~i~
2. Two Idgs roll down a hill. One has a mass of 20 kg and the other 50 kg. Both roll at the same speed.
Which would ~beharderfor
you to stop? Explain usin~ Newton's Laws,
Ik ~0 ~
ty'vQrt.
-bru-.-kJ
Ie,.
~lefiP~~
3. A 2500 kg car accelerates at a rate of 10
;
.,~
.:r:-r Iw-s .M'~. Mu6S S6'
[Je.uIRJ>~) I+-'
.
._,
. rq WI'")
F=tn{}-
mjs2. How much force was required?
F:::. l'V\ (lF ::-LS{OOOrJ
4. Two sumo wrestlers push their opponents each with the same force. If wrestler A accelerates twice
as much as wrestler B, what does this tell us about the masses of A and B?
W ft-01IIe..I
12
D
\
'.
I '-
LI
iM •••
1\0-:5 IW!Q -1J-L r
r ~/
L";'
/
0
-rr
i. )
VV
fL,f{e)'
A.
5. A tow truck pulls on a 2500 kg car with a horizontal force of 15,000 N. The car rolls on a frictionless
road. Draw a free body diagram representing All the forces acting on the car. Does the car accelerate?
.,,,,f,,
t~r:h(,)
1i-7/ ~u-5
-:rJ=:
(j;-r (J:(U\~+"-S,
o
6. A 4 kg birdfeeder
201.1 ..•:51;2()
B'i
l».1~( 50+L
hangs from a rope. Draw a free body diagram showing numerically all the forces'
acting on the birdfeeder.
Pl-i.!t-_<0,: by !.~d:ael .Fhi2.lips at New 12,
oJej'\'.J-
7. A bulldozer pushes a 5000 kg concrete slab with a force of 12,000 N. How much does the slab
I
;
accelerate?
O-~
.
2,4 }""/$'.
8. A 5 kg bowling ball starts at rest, then
IS
' .
~
tJ(j~"+yfO
5h.o{l'lJ.
pushed by a 500 N force forWseconds.
[;(J.): 5 C,,-,
a. What is its speed after 10 s?
SrA.'j
J
0 ':Jteor'.cls
roo fIIj.:.,2.
00-':::'
vf -:v~1- 0.----b .
v f ~0 + lDaLlo');. /000
ff:/:?
b. How far does it travel in 10 s?
bA:;
Vz,t rial L
~I~:;
0(10) 1" t(lOo')(ld-j
9. A 50 N weight is pulled across a rough surface at a constant speed with a pulling force of 8 N. What is
~(\'~50N
the coefficient of kinetic friction?
~~~~.
Y
.
, I'
10. The coefficient
r
( I Pv.1I
_11 t'J
- "D
\"Jf ::/Lc II y\
SON ::,t
t;5:. )f-- /l?'D\ )
.f'-:-D. i ~
j
of kinetic friction between wood and steel is 0.47. A 30 kg block of steel is pushed
and then released on a wood floor and slides to a stop due to friction.
block?
29!.H\J
<' ~F=.;
rt.- '
,
'
'5 ~lJ1J)t1())'-1..t4 tJ
r::
r
,f r
What is the acceleration
of the
c ;.~,~
r\
I",J-
rf~[O.I.p)'(J9Lt)
(3~,i~;;
3D Cr-
rf~i%,'~tv
o-~ 4,~1
_,'
l"iLi
11. A basketball player jumps straight into the air, dunks the ball and hangs on the rim, falls back to the
ground, then lands on the ground and stands in place celebrating.
player for eapc;r:
.
Jump:
J
,
~~)V-Mp
h-iIn-,f:d by t.ti,.r?.P.L Phi.llip
at
~j
fj
7 fq)
12, 2QLl 4:51;"2# ~N
Draw free body diagrams of the
of his motion:
I
Hang:
Falling:
Celebrating:
,
12. Your friend is not a great driver and accidentally runs over his mailbox.
If his car hits the mailbox
with a force of 1300 N, how hard does the mailbox hit the car? .
l300 N
f
,I'
13. Your physics textbook has a mass of 1250 g.
rf\.
a. What is its weight in Newtons?
Fo Q ~5X9-f)
,:::..l,l-S ~
:::ill-,15~
b. If your math textbook has a mass of 1000 g, which book will have a greater force of gravity
acting on it? Why?
Pkt~ILSie:Jbk , I=: ::
fY'o-S) VV1~Yt5 0.-
-force,
~~
ot
9,g) so ~ tw:l-ucyr""';+y .
/'fI -(
'0'
14. What are Newton's Three Laws of motion?.
I s+')
Tr'\LIla- '-
0.,+ re-J
(Ai'\
I
f .(n r"".o-HOI',f(p'\<H ,,-S 1/\ V\'tO-f10f\ (}-.fleA aJ\ ohj{.c,+o.-.\- rl-~ il.n1e-'17 O£,-kl"'l"'1) 1,7 {)J1 (}.rJ,J~
C) bjlL
ft.ll\~~
O{A;tJ;k ~f0L .
F::. ~,O-3rJ-J t:vuy /k1'o"k ho-s
1r.&-')
CM
qiAoJ . MJ opp(;fj;fe., ruxJ,or-
-h,fCL
15. A 40 kg wagon is pulled down the sidewalk so that it accelerates at 3
m/sz. The coefficient of friction
r
is 0.23. How much force is pulling on the wagon? Draw a free body diagram to help you answer.
Fr,~?12N
~p~\l
t{::'jAh
~LO.1.,7X1,91.)
ff~~).Ib~
,j.. ~
. (\0-
Vl/\o.-
~ ~-\- =-(40)(3>
fr.cr::
tw N