UMM- AL -QURA UNIVERSITY
COMMON FIRST YEAR
MEDICAL PHYSICS:
NAME:
GROUP:
Date: OCT 2021
state
ID:
Chess
HOMEWORK FOR CHAPTER 3: Newton’s Laws of motion
1. True or false questions:
a- Inertial mass refers to the quantity of matter of an object:
b- The action and the reaction forces applied on different objects are not necessarily on the same
line of action.
x
c- An object is in equilibrium when a zero net force is applied on this object, then the object can
x motion.
only be at rest or in accelerated
x
d- In the absence of air resistance two objects of different mass are falling from the same height, the
heavy object riches the ground before the light object.
x
e- Between two surfaces of the same nature, the kinetic friction force is higher than the static
friction force.
Asmar
f- The coefficient of static friction depends on the area between the surfaces in contact. x
g- The synovial fluid is a liquid squeezed in the joints to increase the friction between bones.
k
y
------------------------------------------------------------------------------------------------------------------------2. Given the forces 𝐹⃗1 = (106 𝑁)𝑥̂ + (85 𝑁) 𝑦̂ , 𝐹⃗2 = (−70 𝑁) 𝑥̂ + (55 𝑁) 𝑦̂ applied on an object
of mass 12 kg.
a
Find:
362 1 5
ftp.alsetctunt.is
13211,7
ylmes
a- The resultant force.
g
LE
b- The components
of the acceleration vector.
EE It
I
xp
g
-----------------------------------------------------------------------------------------------------------------------------3. A crate of mass 𝑚 = 25 𝑘𝑔 is pulled with a force of magnitude 𝐹 = 140 𝑁 and a direction 𝜃 = 27° on
LE floor (Figure 1). Assume friction is negligible.
a horizontal
aaxis
a
fo fr fatty o
Calculate:
m fsin
F
fcosc
i.mu
a
a. The acceleration of the crate.
L3magnitude of the normal force.a
b. The
Ee
gases
4 tntu
say
zsca.rsnosiness
la.mn
The crate is now on a plane inclined by an angle of 30 o. The force F is
eliminated but a friction of magnitude 𝐹𝑟 = 50 𝑁 is exerted between thed
crate and the surface of plane (Figure 2).
c
toes
Calculate:
massinei
ma
t
c. The new acceleration of the crate.
z
d. Theymagnitude
of the normal force.
assassins
so a
3775 2.9
a a.ams
fysfn mgeosco.io
e mge.scaasa.geseu.n.snsee
y
ne
nosing
fear
4. A 2.0-kg box is at equilibrium state at the position (1) on an inclined surface with an angle 𝜃 = 20°.
UMM- AL -QURA UNIVERSITY
COMMON FIRST YEAR
MEDICAL PHYSICS:
NAME:
GROUP:
Date: OCT 2021
other
a
ID:
a. The box is moved to position (2) and remains in equilibrium at that position. What is the kind of this
equilibrium (Neutral -stable – unstable)?
b. In this case calculate the static friction.
c. The box begins to slide when the angle becomes 𝜃 = 28°. Calculate the coefficient of static friction.
d. After the box is starting to slide the angle is reduced to 𝜃 = 22° to keep the box sliding at constant
speed. Find the coefficient of kinetic friction.
(1
)
(2
)
no
f
kg
ngcost
ng
hog
ng
2201
20
messineo
Is MYsince
f fu
fee messing fr
zeq.ggsinew
L
mgc.sc
I
Mk
he
so
3
Fy
µ
IsMsfn'smgsines
s
tanczo o.es
Ms
ns.t.no
p g
f
o
mysinct
In mycoses o
fMtn
msmgc.se
0,4
mysince
fr
n
ma
q
I
messineo fseman
o
SC 7219.81cosezi
As o
ago
toe
r
f
r
Fa
d
massine Micmac.se
mane
Mastancais
on