CH4: Dynamics

Question 1

how does a force change the motion of an object?

Answer 1

• making a stationary object start moving
• change the speed of the object
• change the direction of an object

Question 2

define Newton’s 1st Law

Answer 2

Newton’s 1st Law states that every object will continue in its state of rest or uniform motion unless a resultant force acts on it.

Question 3

define Newton’s 2nd Law

Answer 3

Newton’s 2nd Law of motion states that when a resultant force acts on an object of constant mass, the object will accelerate in the direction of the resultant force.
Fnet=ma
(net force= mass x acceleration)

Question 4

define friction

Answer 4

a type of force that exists when two surfaces are in contact of each other and opposes motion.

Question 5

state the advantages of friction

Answer 5

• stop/slow down an object that is moving
• allows for almost all forms of movements

Question 6

state the disadvantages of friction

Answer 6

• causes wear and tear to the objects in contact
• reduces the efficiency of moving parts

Question 7

ways to overcome friction

Answer 7

• applying a layer of lubricant between surfaces in contact
• attaching ball bearings between moving parts of machine and wheels

Question 8

define Newton’s 3rd Law

Answer 8

Newton’s 3rd Law states for every forward force exerted, there will always be a backward force exerted. These two forces are same in magnitude but in opposite directions of each other.

Question 9

in accordance with Newton’s law, what happens when a parachutist first jumps off the plane and when she opens the parachute?

Answer 9

when the parachutist first jumps off the plane, she is pulled downwards by gravity, which means that she will accelerate down