TopicSlidesMinutes 1 Displacement Vectors Kinematics Graphs Power Springs Shadows 39 9 Field of Vision Colors Concave mirrors Convex mirrors Refraction Lenses Optical Power 618 Energy

Energy is the capacity to do work (We see the object going faster) (We see the object going higher) (We can feel the heat and hear the sound) Just like money is the capacity to purchase In an ideal system, there is no friction and thus no work is done to overcome friction (no energy loss). If an object is not being accelerated, not being raised, and there is no friction (ideal), no work is done. R E M E M B E R There are three types of work that can be done.

Accelerate Raise Overcome friction f “Constant velocity” The force must be parallel to the distance. I M P O R T A N T

The vertical component makes the object lighter by 86.7 N. Accelerate Raise Overcome friction “Constant velocity” f = 50.0 N 100 N Cos 60 Since the object is moved at constant velocity, the work (energy) goes to overcome friction and the energy is lost. Since the object is moved at constant velocity, the work (energy) goes to overcome friction and the energy is lost.

The vertical component makes the object lighter by 64.3 N. Accelerate Raise Overcome friction “Constant velocity” f = 76.6 N 100 N Cos 40 Since the object is moved at constant velocity, the work (energy) goes to overcome friction and the energy is lost. Since the object is moved at constant velocity, the work (energy) goes to overcome friction and the energy is lost.

If the object is moved at constant velocity, the work (energy) goes to overcome friction and the energy is lost. If the object is moved at constant velocity, the work (energy) goes to overcome friction and the energy is lost. If the object is accelerated, the work (energy) goes to the object in the form of kinetic energy. In this case, all the applied force goes to do the work and it is the most efficient method to pull the object. Accelerate Raise Overcome friction

Energy in Energy out No friction (no energy loss) Example (1 N)(100 m) = 100 J (100 N)(1 m) = 100 J 100 J in 100 J out IMA = 100

Click As illustrated below, there are two families of simple machines each family consists of three types of machines:

A hammer falls from a scaffold and 1.5 s later strikes the ground with a kinetic energy of J. What is the weight of the hammer? Click E X A M P L E Don’t confuse weight with mass!

In flattening the ground of a tennis court, Robert uses a 20 kg roller as illustrated below. Click If Robert pushes the roller a distance of 10 m with an applied force of 200 N, how much work does he do?. Work Slide:

In flattening the ground of a tennis court, Robert uses a 20 kg roller as illustrated below. Click If Robert pulls the roller a distance of 10 m with an applied force of 200 N, how much work does he do? Work Slide:

In flattening the ground of a tennis court, Robert uses a 20 kg roller as illustrated below. Click Which is easier to do, push or pull the roller? PushingPulling It is easier to pull since in pulling the vertical component of the pull is upward thereby reducing the weight. However, it is more effective to push the roller as the vertical component will increase the weight. Work Slide:

A 20 g bullet has a velocity of cm/s. Calculate its kinetic energy. Click Convert grams to kilogramsConvert cm/s to m/s 20 g = 0.02 kg cm/s = 250 m/s Kinetic Energy Slide:

An object having a mass of 5 kg is traveling at 6 m/s. It accelerates to a velocity of 12 m/s. How much work was done to accelerate the object? Click Kinetic Energy Slide:

A 2 kg mass, moving horizontally at 10 m/s, slides up a frictionless incline as illustrated in the diagram below. Click How high up the incline does the mass rise? Potential Energy Slide:

Starting with an initial velocity of 10 m/s, a 2 kg object slides down a frictionless shoot as illustrated in the following diagram. Click How high up the incline does the mass travel before coming to a stop? Potential Energy Slide:

Which one of the following simple machines cannot be used to lift a 100 kg load by applying a force less than 980 N? Click A) IB) I and IIIC) I and IVD) I, II and IV Machines Slide:

Betty uses the hoist illustrated on the right to raise a mass of 200 kg. If she can pull the rope 5.0 metres in a time of 10 seconds, what is Betty’s power output? Note: Disregard friction. Click A) 17.0 W B) 100 W C) 163 W D) 980 W I.M.A. = 6 (6 ropes) Machines Slide:

Which two of the following simple machines have the same ideal mechanical advantage? Click A) 1 and 2 B) 1 and 4 C) 2 and 4 D) 3 and IMA = 5IMA = 4 Length Machines Slide: 5. 10

… and good luck!