2 Newton’s First Law Chapter 11 an object at rest remains at rest and an object in motion maintains its velocity (stays in motion) unless it experiences an unbalanced force (outside force).Aka Law of Inertia
3 INERTIA tendency of an object to resist being moved or if object is moving, to resist a change in speed or direction until an outside force acts on object.All objects resist changes in motionrelated to an object’s mass.Objects with small mass have less inertia than objects with large mass
4 INERTIA EXAMPLE Chapter 11 Seat belts and car seats provide protection.Because of inertia, you slide toward the side of a car when the driver makes a sharp turn.When the car you are riding in comes to a stop, your seat belt and the friction between you and the seat stop your forward motion.
5 m F a Newton’s Second Law 1 N = 1 kg 1 m/s2 unbalanced force acting on an object equals object’s mass times its acceleration.Force = mass accelerationF = maSI Unit: newtons (N)1 N = 1 kg 1 m/s2mFa
7 m F a FORCE F = ? F = ma m= 175 kg F = (175 kg) (0.657 m/s2) Zookeepers lift a stretcher that holds a sedated lion. The total mass of the lion and stretcher is 175 kg, and the lion’s upward acceleration is m/s2. What is the unbalanced force necessary to produce this acceleration of the lion and the stretcher?GIVEN:F = ?m= 175 kga = m/s2WORK:F = maF = (175 kg) (0.657 m/s2)F = 115 NmFa
8 m F a FORCE F = ? F = ma m= 1.6 x 103 kg F = (1.6 x 103 kg) (2.0 m/s2) What is the net force necessary for a 1.6 x 103 kg automobile to accelerate forward at 2.0 m/s2?GIVEN:F = ?m= 1.6 x 103 kga = 2.0 m/s2WORK:F = maF = (1.6 x 103 kg) (2.0 m/s2)F = 3.2 x 103 NmFa
9 m F a FORCE F = 1.4 N m = F/a m= ? m = 1.4 N / 9.8 m/s2) a = 9.8 m/s2 A baseball accelerates downward at 9.8 m/s2. If the gravitational force is the only force acting on the baseball and is 1.4 N, what is the baseball’s mass?GIVEN:F = 1.4 Nm= ?a = 9.8 m/s2WORK:m = F/am = 1.4 N / 9.8 m/s2)m = 0.14 kgmFa
10 m F a FORCE F = 895 N a = F/m m= 655 kg a = 895 N / 655 kg a = ? A sailboat and its crew have a combined mass of 655 kg. Ignoring frictional forces, if the sailboat experiences a net force of 895 N pushing it forward, what is the sailboat’s acceleration?GIVEN:F = 895 Nm= 655 kga = ?WORK:a = F/ma = 895 N / 655 kgF = 1.37 m/s2mFa
12 Law of Universal Gravitation Chapter 11Law of Universal GravitationAll objects in universe attract each other through gravitational forceSir Isaac Newton (1642–1727)Universal Gravitation Equationm1 and m2 are masses of two objectsd distance between two objectsG constant
13 Law of Universal Gravitation All matter is affected by gravity.Two objects, whether large or small, always have a gravitational force between them.Gravitational force increases as mass increases.Gravitational force decreases as distance increases.
14 Free Fall Acceleration motion of a body when only force of gravity is acting on body.constant near Earth’s surface.g =9.8 m/s2
15 Weight weight = mass free-fall acceleration equal to mass times free-fall acceleration.weight = mass free-fall accelerationw = mgWeight is different from mass.Massmeasure of amount of matter in an object.Weightgravitational force an object experiences because of its mass.influences shape
16 Terminal Velocityconstant velocity of a falling object when force of air resistance is equal in magnitude and opposite in direction to force of gravity
18 Projectile Motion and Gravity Chapter 11Projectile Motion and Gravitycurved path an object follows when thrown, launched, or otherwise projected near surface of Earth.applies to objects that are moving in two dimensions under the influence of gravity.has two componentshorizontal and vertical.two components are independent.
20 Newton’s Third Law Chapter 11 for every action force, there is an equal and opposite reaction force.Forces always occur in action-reaction pairs.Action-reaction force pairs areequal in size andopposite in direction.
21 Action and Reaction Forces Chapter 11Action and Reaction ForcesForce pairs do not act on the same object.Equal forces don’t always have equal effects.example, the action force of Earth pulling on an object and causing it to fall is much more obvious than the equal and opposite reaction force of the falling object pulling on Earth.
22 momentum = mass velocity Chapter 11Momentumquantity defined as product of the mass and velocity of an object.momentum = mass velocityp = mvMoving objects have momentum.the more mass an object has, the greater its momentum is.faster an object is moving, the greater its momentum is.When you force an object to change its motion, you force it to change its momentum.
23 m p v Momentum p = ? p = mv m= 6.00 kg p = (6.00 kg) (10 m/s) Calculate the momentum of a 6.00 kg bowling ball moving at 10.0 m/s down the alley toward the pins.GIVEN:p = ?m= 6.00 kgv = 10 m/sWORK:p = mvp = (6.00 kg) (10 m/s)p = 60 kg x m/s down the alleympv
24 m p v Momentum p = ? p = mv m= 75 kg p = (75 kg) (16 m/s) v = 16 m/s A 75 kg speed skater moving forward at 16 m/s. Calculate the momentum.GIVEN:p = ?m= 75 kgv = 16 m/sWORK:p = mvp = (75 kg) (16 m/s)p = 1200 kg x m/s forwardmpv
25 m p v Momentum p = ? p = mv m= 135 kg p = (135 kg) (16.2 m/s) A 135 kg ostrich running north at 16.2 m/s. Calculate the momentum.GIVEN:p = ?m= 135 kgv = 16.2 m/sWORK:p = mvp = (135 kg) (16.2 m/s)p = 2190 kg x m/s northmpv
26 m p v Momentum p = 5 kg x m/s forward v = p/m v = 5 kg x m/s / 0.8 kg Calculate the velocity of a 0.8 kg kitten with a momentum of 5 kg x m/s forward.GIVEN:p = 5 kg x m/s forwardm= 0.8 kgv = ?WORK:v = p/mv = 5 kg x m/s / 0.8 kgv = 6.3 m/s forwardmpv
27 Law of Conservation of Momentum Chapter 11Law of Conservation of Momentumtotal amount of momentum in an isolated system is conserved.When a moving object hits a second object, some or all of the momentum of first object is transferred to second object.Momentum can be transferred in collisions, but total momentum before and after a collision is same.rocket propulsion.Cars collidedBilliards