Tuesday, 12 June 2012It is a change in the position of an objectwith respect to time.
Copy Parameter Unit Distance, d Meters, m Time, t Seconds, s Speed, vav Meters per second, ms-1 Displacement Meters, m Velocity, v Meters per second, ms-1 Acceleration, a Meters per second per second, ms-2
Copy *Displacement is a vector and so must have a distance value and a direction. *Distance just has a value.
Copy *Velocity is also a vector and so must have a speed value and a direction. direction *Speed just has a value.
Copy *How much the speed is changing over time. *Acceleration means speeding up, deceleration or negative acceleration is slowing down.
Copy A journey from Dunedin to Christchurch Time from start Distance from (h) Dunedin (km) 0 0 1.5 100 Changing tyre 2.0 100 4.5 275 Eating lunch 5.0 275 6.0 360
Copy Draw a graph using this data. When drawing graphs, follow these steps: • Decide what data goes on the x-axis and what data goes on the y-axis. • Title your graph and label the axes, remember to include units. • Have even scales on your axes. (i.e. 1, 2, 3, 4 … not 1, 2, 5, 8 …) • Plot your points on the graph. Make sure to start at 0. • Connect points with a ruler for distance-time and speed-time graphs.
1. The vehicle covered 100km in the first two hours.2. The vehicle was stationary between 2 hours and 5 hours.3. Between 5 hours and 8 hours the vehicle covered a further 180 km.4. Between 8 hours and 11 hours, the vehicle was stationary.
When reading a stopwatch you see… 00:02:30.155. How would you say this time??6. How many seconds in this time?7. How many minutes in this time?
1. Split into 2 groups.2. Decide on 1 person to be each of the following: • 3x Timekeepers • 3x Recorders • Runner • Walker3. On the field in the front of the school, each group will measure out a track of 30m.4. The runner and walker both position themselves at the start. Both will set off at the same time.5. One timekeeper is at the 10m mark, one at the 20m mark and one at the 30m mark. Each time keeper times when the runner and walker passes their mark .6. Recorders will write down the times.
Copy Time at Time at Time at Time at 0m (s) 10m (s) 20m (s) 30m (s) Runner 0 2.40 3.00 5.00 Walker 0 6.00 12.00 19.00
Copy*Speed measures distance the distance v average = travelled in a given time. time d v av = d t How to get kmh-1? vav t Multiply ms-1 by 3.6 Eg. 100ms-1 x 3.6 = 360kmh-1
Copy *We can use the slope of a distance – time graphs to find the Rise speed of an object. *To do this the graph Slope = line must be Run straight.
*Plot a speed – time graph using this data.*Plot the two skiers on the same axes.*Draw a straight line of best fit for both skiers (use a ruler). Speed (ms-1) time (s)
*Calculate the slope of the two skiers.*How quickly was skier 1 accelerating?*How quickly was skier 2 accelerating?
Aim of the experiment: To measure how the height of a ramp affects the speed of a marble covering 1m along flat ground.Equipment:•2x 1m rulers (one with a dip in it)•Clamp stand•Stopwatch•Marble
Method:Conduct this experiment in pairs (or groups of 3 max).3.Measure a clamp stand so that it is 10cm above theground.4.Place a ruler on the clamp stand. This will work as theramp.5.At the end of the ramp (lying flat on the ground), placethe second ruler.6.Let the marble travel down the ramp.7.Start timing the marble when it hits the flat surface, andtime how long it takes to travel the 1m.8.Repeat the experiment with the clamp at 10cm, so thatyou have 3 times.9.Repeat the experiment with the clamp at 20cm, 30cmand 40cm. Make sure you have 3 times for each height.
Processing your data:3.Average your times for each ramp height.4.Draw a graph using the averages.5.From your data, calculate the average speed ofthe marble for each ramp height.6.Calculate the acceleration of the marble foreach ramp height.
Copy This is calculated from speed-time graphs. To do this, graphs need to be split into squares or rectangles or triangles. Once you have split up your graph, use the formula to find the area of each shape: Square or rectangle = x-axis X y-axis [base X height] Triangle = ½ X(x-axis X y-axis) [½ X base X height]
You may have more than one shape on agraph.When this happens, work out the area ofeach shape separately and then add theareas together.Handouts x2 – Finding the Area underGraphs and Distance from a speed-time graph