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WARM-UP:HOMEWORK CHECKPlace on your desk:
*Calculator*Orange homework chart
*Newton’s 1st Law Worksheet
1) What is the weight of a 12 Kg stone?
2) Calculate in Newtons the weight of a 1.5 Kg melon. What is weight in pounds? [1Kg=2.2 lbs]
Agenda1) Warm-Up 5 min
2) Coupons!3) Vocab. Words 10 min
4) Newton’s 2nd Law 15 min
5) Board Notes for 2nd law 10 min
6) Newton’s 2nd Law Worksheet 30 min
7) Balloon Rocket mini-lab 15 min
LEARNING GOALS: •A force is a push or pull.•Inertia is a property of matter that depends only on mass.•Acceleration is directly proportional to net force.
HOMEWORK DUE:Newton’s 1st Law WS
10-05- 11
120 N
FW=(m*g)=(1.5Kg)(9.8m/s2)
=14.7 N* (1Kg/9.8N)(2.2 lb/1Kg)
Vocab.1. Law of Inertia: every object (body) continues in a state
of rest, or motion in straight line at constant speed, unless it is compelled to change by forces exerted upon it.
2. Mass: quantity of matter in an object; measure of inertia that an object exhibits in response to any effort made to start or stop state of motion. SI unit Kg.
3. Newton: SI unit of force; amount of force needed to accelerate 1 kg of mass at a constant acceleration. 1 N=9.8 m/s2
4. Normal Force: the supportive force that is perpendicular “normal” to the surface—vertical direction.
Newton’s Second Law of Motion
FORCE AND ACCELERATION
• C. Newton’s 2nd Law of Motion• Law explains what happens when there is
either a single applied force or 2 more applied forces whose vector sum is NOT zero.
• (Forces are what produce acceleration)• Law states: “the effect of an applied forced is to
cause the body to accelerate in the direction of the force.”
• The acceleration is in direct to proportion to the force & inversely proportional to the mass of the body.
• (Combination of forces act on objects & it is the net force (Fnet) that accelerates the object).
• If a body is at rest & a force acts on the body, then the body will move in the direction of the force applied & will move faster while the force is continued.
• If a body is moving in a straight line & force acts, then the force will increase the speed while force acts & it will move in the direction of the force.
• Therefore, velocity changes & acceleration is not zero. If different forces are applied to the object, the magnitude of the acceleration will be directly proportional to the amount of force. But, will be inversely proportional to the mass.
• Example: net force doubled, acceleration doubled. Mass doubled, then acceleration…
• D. Solving Force vectors• Equilibrium is the state of body in which there
is no change in its motion. A body in equilibrium is either at rest or moving at constant speed in a straight line.
• When there are NO unbalanced forces acting on a body, the vector sum of all the forces acting on the body is zero.
• So each force is equal to the other. To find the equilibrant of the 2 concurrent forces (acting at the same time), find the vector first.
• Since the equilibrant must balance the effect of the resultant, the equilibrant must have the same magnitude but different & opposite direction.
• Equilibrant force is the single force that if applied at the same point produces equilibrium.
FORCES CAUSE ACCELERATION
There is always MORE than one force acting on
an object at one time. Forces are found in “pairs”.
5.2 Mass Resists Acceleration
As the mass of an object increases, the
ability to accelerate it using the same force
decreases.
Think about a grocery cart…
When the cart is empty, it is easy to push.
The cart easily accelerates with simple pushing.
What about when the cart is full and the mass is greater? (see example)
The higher the mass of the cart, the harder you have to push.
What is different with the 2 carts?
5.3 Newton’s Second Law
Using variables, we get the equation:
F A = m
Because we always use the same units, we can also say…
Net ForceAcceleration = Mass
Computer log-in!Formula Sheet!
Newton’s 2nd Law WS
Balloon RocketReturn: Straws, washers
string
B2
B4
A3
A4
DUE TODAY:• Newton’s 2nd law Notes (KEEP)• Balloon Rocket Qs
DUE NEXT CLASS:• Newton’s 2nd law worksheet• Bring Calculator!
“The whole secret of life is to be interested in one thing
profoundly and in a thousand things well.”
Horace Walpole
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