dynamics topic 3

Front

si unit and si base unit of force

Back

newton, kg m s^-2

Front

def and types of ocntact and non contact forces

Back

contact foces act when two interacting objects have phsyical contact over each other including ncf, friciotnal force, drag froce and elastic froce

non contact forecs act over a distance without physical contact between two interacting object and include gf, magnetic force and electrical force

Front

define weigth and mass and all specific deets

Back

weight is the force of gravity acting on a body and it s is a vector quantity hence varies with position. si unit is newton and a calibrated spring balance is used to measure it

mass us the amount of matter in a body and it is a scalar quantity hence does not vary with position and it has the si unit of kg and it is measured using comparison with standard mass like electronic mass balance

Front

define gracitational field, gravitational field strength

Back

gravitational field is the region in which a mass experiences a force due to gravitational acceleration.

gravitational field strength is the gravitational force per unit mass (9.81 n kg^-1)

Front

weight forumla

Back

w= mg

Front

define inertia

Back

inertia refer tot he resistance of a body to resist a change in the state of rest or motion of the body

Front

define normal contact force + characteristics

Back

normal contact force is the perpendicular force exerted by the surface of one object on the surface of another when they are in physical contact and it prevents the objects from passing through each other

1. only exists when an obj is in contact with sth else

2. 2. alw perpendicular to contact surface and its direction is through obj of interest

3. 3. does not alw pass through the CG of obj

4. 4. not alw equal too weight of obj (when obj is on slope, vertical acceleration --> up is more n, down is less n) other vertical forces)

Front

frictional force

Back

friction is the contact force that acts between objects that opposes or tends to oppose or resist motion

1. 1. smooth --> no friction, rough --> friction

2. 2. directed parallel to the surface

3. 3. magnitude is proportional to the normal force and the type/nature of contact surfaces

4. 4. always act opposite to direction of motion at the point of contact

   factors affecting :

5. 1. type of surface

6. 2. amt of normal contact force (ie weight )

Front

drag force

Back

fluid resistance (l or g)

factors:

1. 1. increases with speed/ velocity of obj

2. 2. increases with surface area of object

3. 3. increases with density of object

4. 3. affected by shape --> streamlined better than irregular or blunt

Front

tension

Back

tension is the force exerted by a rope string cabale or other flexible object on another obejct

it always exerts a pull on obj and is directed away from object and along the length of the string