Review for Summative Assessment

Review for Summative Assessment

What is the summative assessment?

• We will be doing a summative assessment on Wednesday

• It is designed to measure how much you've learned since the beginning of the year

• It will not be graded for accuracy - everyone who completes it on time will get 20 points

• It will cover everything we've learned up until this point - measurement, units, graphing, motion, forces, energy, and electricity

Measurements

• In physics, we make precise and accurate measurements that can be compared to calculated values

• We deal with two main types of quantities - scalar and vectors

• Scalars are just numbers and do not have a direction. Examples are electric charge, mass, temperature, distance, volume, energy, etc.

• Vectors are quantities that depend on direction. Quantities include acceleration, velocity, force, magnetic field strength, etc.

Multiple Choice

Which of the following is a scalar?

• Force

• Acceleration

• Time

• Velocity

SI Units and Conversions

• SI unit system is the measurement system used in physics and scientific discourse

• The base SI units: meter (length), kilogram (mass), second (time), K (temperature)

• We also learned that we can convert metric units quite easily using the metric prefixes

SI Ladder

• To convert between the units we find the prefix of the unit we are converting from and the prefix of the unit we are converting to

• We then count how many steps we move up or down the ladder

• We move our decimal point the appropriate number of places

SI Ladder

• For example, to convert 1200 mm to m we first discover that we go 3 places to the left

• We then move our decimal point 3 places to the left and then we find that there are 1.2 m in 1200 mm

Multiple Choice

What is the SI unit of mass, length, and time?

• m, g, s

• m, kg, s

• cm, kg, min

• in, lbs, hour

Multiple Choice

How many grams (g) are there in 20 kilograms (kg?)

• 2,000 g

• 20,000 g

• 200 g

• 20 g

Graphing

• The dependent variable goes on the y-axis

• The Independent variable goes on the x-axis

• The slope of the graph tells us how much the rate of change of the dependent variable with respect to the independent variable

• The units of the slope are the units of the dependent variable divided by the independent variable's units

Calculating slope

• Select 2 points on the graph

• Identify their x and y coordinates

• Find the change in y

• Find the change in x

• Divide to find the slope

• The units of the slope are the units of the DV divided by the IV

Multiple Choice

What is the slope of the following graph?

• 5 m/s

• 8 m/s

• 10 m/s

• 20 m/s

Multiple Choice

For this graph of mass versus volume, what are the correct units of the slope?

• mL/g

• g/mL

• kg/L

• g

• mL

Motion

• We can describe the motion of objects using concepts like speed and acceleration

• The average speed of an object is the distance traveled divided by the time 

•  $s=\frac{d}{t}$  

• The acceleration of an object is the rate of change of velocity

Multiple Choice

What is the average speed of the object represented by the red line?

• 5 m/s

• 10 m/s

• 7 m/s

• 8 m/s

Multiple Choice

How far does a dog run if he runs at 10 m/s for 5 s?

• 2 m

• 100 m

• 50 m

• 8 m

Multiple Choice

The image shown here is of a velocity-time graph. When is the object speeding up?

• From 0 to 5 seconds

• From 5 to 10 seconds

• From 6 to 13 seconds

• From 0 to 12 seconds

Forces and Newton's 2nd Laws

• Force is a vector - depends on direction

• To find the total force acting on an object we must add up all the forces

• Newton's 1st Law objects want to continue in a straight line at constant speed

• Newton's 2nd Law

•  $F=ma$  

• Newton's 3rd Law - the force on object A from object B is equal and opposite to the force on object B from object A

Multiple Select

Newton's 2nd Law says which of the following

• The greater the force, the greater the acceleration

• The greater the mass, the less the acceleration

• The greater the mass, the greater the acceleration

• Acceleration is always constant

Multiple Choice

If a 2 kg object is pulled to the right by a force of 20 N and then pulled to the left by a force of 12 N, what is the acceleration of the object

• $6\ \frac{m}{s^2}$ to the right

• $4\ \frac{m}{s^2}$ to the right

• $4\ \frac{m}{s^2}$ to the left

• $10\ \frac{m}{s^2}$ to the right

Work and Energy

• To transfer energy, work must be done

• There are many different types of energy - kinetic, gravitational potential energy, elastic potential energy, chemical potential energy, thermal energy, electromagnetic energy, etc.

• The law of conservation of energy says that energy can neither be created nor destroyed - it is only transformed from one form to another

• The total energy of a closed system is constant

Multiple Choice

You roll a ball down a ramp. It starts with gravitational energy and then when it reaches the bottom it is transformed to kinetic energy. The ball eventually comes to a stop. What can you conclude?

• The system has lost energy

• The system has gained energy

• The energy is constant; it was just turned into heat because of friction

Electricity

• Charge can neither be created nor destroyed

• Objects can be charged by conduction, induction, or friction

• Materials that conduct electricity are called conductors

• Electric current is the rate at which charge flows

• An electric circuit contains a voltage source and a closed conducting path

• Ohm's Law expresses the relationship between voltage, current, and resistance

•  $V=IR$  

Multiple Choice

What is wrong with the following circuit?

• Lacks a closed conducting path

• Lacks a voltage source

• Both