PHysics lecture

Question 1

1.Push or a pull acting on an object.
2.An interaction between two bodies or between a
body and its environment.
3.A vector quantity

Answer 1

Properties of forces

Question 2

1.Change the dimensions or shape of a body (static
force)
2.Change a body’s motion (dynamic force)

Answer 2

Effects of forces

Question 3

Magnitude

Answer 3

– describes “how much” or “how hard”
the forces acts.

Question 4

it indicates the line of action where the
force will be acting.

Answer 4

Direction

Question 5

line in which the force vector is a
segment; imaginary line extended indefinitely along
the vectors in both dire

Answer 5

line of action

Question 6

KIND OF FORCES

Answer 6

Parallel Forces – forces whose
lines of action are parallel or
do not cross each other.
Concurrent Forces – forces
whose lines of action meet at
a common point.

Question 7

Equilibrium Under the
Action of Concurrent Forces

Answer 7

A branch of mechanics that deals with
bodies in equilibrium is called statics. Bodies
will be in equilibrium when they are at rest
or moving at constant velocity. For a body to
be at rest or moving at constant velocity , it
must be acted on by no forces, or by several
forces such that their vector sum – that is,
the net force – is zero.

Question 8

COMMON TYPES OF FORCES

Answer 8

Weight - Gravitational force of
attraction by the earth on an
object.
▪ Always drawn vertically
downward and concentrated
at the center of gravity of an
object which is usually at the
center of a regular shaped
body
Tension- Force exerted by objects
like string, cable, rope,
wire, cord and the like on
another object when they
subjected to a pull at their
ends.
▪ Drawn along the direction
of the string.
Normal force -A contact force perpendicular to the contact surface that
prevents the two objects from passing through one
another.
▪ Force exerted by the surface of an object on another object
which is lying on the surface.
Frictional force-A contact force parallel to the contact surface.
▪ Drawn parallel to the surface and opposite to the
direction of motion

Question 9

Static friction

Answer 9

acts to prevent objects from
starting to slide.

Question 10

Kinetic friction

Answer 10

–acts to try to make sliding object
to stop.

Question 11

Units of gravity

Answer 11

9.81 m/s^2 = 980 cm/s^2 =32.3 ft/s^2

Question 12

Units of forces (newton)

Answer 12

1N = kg(m/s^2)

Question 13

Unit of forces (dynes)

Answer 13

1 dyne=g(cm/s^2)

Question 14

Unit of forces (pound force)

Answer 14

1lbsubf= slug(ft/s^2)

Question 15

Unit of forces (poundal)

Answer 15

1poundal=1lbsubm(ft/s^2)

Question 16

Units of mass

Answer 16

1kg=1000g=6.852x10^-2slug=2.205lb

Question 17

Unit of time

Answer 17

1min=60sec =1 hr=3600seconds