Title: Newtons Second Law of Motion
1Newtons Second Law of Motion
2Bell Work
- Identify three forces acting on a speeding
bullet. - Why do cars sometimes skid going around corners
on icy roads?
3Objectives
- Define and apply Newtons second law of motion to
real life situations. - Relate the acceleration of an object to the mass
of the object and the force applied to the object.
4Newtons Second Law of Motion
- This law states that an unbalanced force on an
object causes the object to accelerate in the
direction of the force.
5Force of wind
These forces are unbalanced so the boat
accelerates in the direction of the unbalanced
force.
20-30 mph
Air/Water Resistance
6Gravity
Unbalanced Forces
Table
If gravity becomes greater than the upward force
of the table, the papers will accelerate downward.
7Wagon moves this way
Unbalanced
Force
Applied
8Force, Acceleration, and Mass
- The greater the force applied to a given object,
the greater its acceleration.
9Force, Acceleration, and Mass
- For a given force, the greater the mass of an
object, the smaller its acceleration and
vice-versa.
10Newtons Second Law in Real Life
- Why would a truck take longer to accelerate when
the driver hits the gas if it were loaded with
bricks than if it were empty? - How might you design a car to achieve maximum
acceleration?
11Newtons Second Law in Real Life
- Using Newtons second law of motion, explain why
larger trucks usually need more distance to stop
than do smaller trucks.
12Science, Technology, Sports
- Friction is the main force that slows the speed
of athletes in sports such has skiing, swimming,
cycling, speed skating, and running. How can
these athletes combat the effects of friction?
13Formula for Newtons Second Law of Motion
- Newtons second law of motion can be expressed by
the formula F ma. - F stands for force, m stands for mass, and a
stands for acceleration.
14Formula for Newtons Second Law of Motion
- According to this formula, if the force is
constant and the mass increases, what will happen
to acceleration?
15Question
- Identical twins are riding in identical wagons. A
friend gives the first wagon a stronger push than
the second. Which twin will experience greater
acceleration?
16Question
- Would a car towing a boat take less, the same, or
more time to accelerate than it would without the
boat? Explain.
17Question
- What will happen to the acceleration of an object
if the mass decreases and the force is constant?
18Question
- If two identical objects accelerate at the same
rate, what must be true of the force applied to
each object?
19Review
- Use Newtons second law of motion to explain why
a free-falling object accelerates. - How is the acceleration of an object affected by
the force applied to it?
20Challenge
- Using the formula a f/m, explain why all
objects in free fall have the same acceleration,
regardless of mass.