forces and free-body diagrams by corina bot. a force is a vector quantity (=> has both magnitude...
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Forces and Free-body diagrams
By Corina Bot
A force is a vector quantity (=> has both magnitude and direction). To fully describe the force acting upon an object, you must describe both the magnitude (size or numerical value) and the direction.
It is common to represent forces using diagrams in which a force is represented by an arrow. The size of the arrow is reflective of the magnitude of the force and the direction of the arrow reveals the direction which the force is acting. (Such diagrams are known as free-body diagrams)
http://www.glenbrook.k12.il.us/GBSSCI/PHYS/Class/newtlaws/u2l2a.html
2111
s
mkgNewtonN
If we push the block harder and harder, the frictional force will increase, until it reaches a
maximum (in this case, 2.5N). If we push harder still, (say, 2.6N), the block will
start to move, because we're now pushing harder than the frictional force.
Frictional Force Nkk FF
http://www.glenbrook.k12.il.us/GBSSCI/PHYS/Class/newtlaws/u2l2a.htmlhttp://home.clara.net/darvill/enforcemot/friction.htmhttp://www.ac.wwu.edu/~vawter/PhysicsNet/Topics/Dynamics/Forces/Tension.htmlhttp://en.wikipedia.org/wiki/Force
Tension Force
Spring Force
Contact Forces
Normal Force
Applied Force
Frictional Force
Tension Force
Spring Force
Normal Force
Gravitational Force gmFg
nF
gF
Action-at-a-Distance Forces
Gravitational Force
Electrical Force
Magnetic Force
Iron filings and compasses show the shape and direction of the magnetic field
http://en.wikipedia.org/wiki/Forcehttp://en.wikipedia.org/wiki/File:EfieldTwoOppositePointCharges.svghttp://www.school-for-champions.com/science/magnetic_detection.htm
Electric vector field surrounding two opposite point charges. Red is positive, green is negative.
An initially stationary object - allowed to fall freely under gravity drops a distance which is proportional to the square of the elapsed time.
gmFg Gravitational Force
x
y
0
A mini-car is pulling a block, with a force of 190N, as shown in figure. The block has a mass of 15 kg and the coefficient of kinetic friction between the bottom of the block and the surface is 0.6. Find the acceleration of the cart.
Fapp=190 N
m = 15 kg
k 0.6
ax = ?
15 kg
a
kF nF
appF
gF
aBy definition:
gmF
FF
g
Nkk
20
1
,
,
yyynet
xxxnet
amFF
amFF
From equation (1):
3156.0190
15190
15190
xN
xNk
xk
xkappx
akgFN
akgFN
akgFN
amFFF
From equation (2):
Ns
mkggmFF
FF
amF
gN
gN
yy
1478.915
0
0
2
From equation (3):
278.6
15
8.101
158.101
152.88190
151476.0190
s
m
kg
Na
akgN
akgNN
akgNN
x
x
x
x
Fapp=190 N
m = 15 kg
mk = 0.6
ax = ?
x
y
0kF nF
appF
gF
a
20
1
,
,
yyynet
xxxnet
amFF
amFF
A descendant of the original apple tree can be seen growing outside the main gate of Trinity College, Cambridge, UK, below the room Newton lived in when he studied there.