Describing movement
These are model answers, which are not designed to be prescriptive. Good answers should contain the key scientific ideas covered in the model. Section ‘d’ and ‘e’ questions in particular are intended to stretch students, and novel applications of knowledge should be rewarded.The level icons are a guide to the level a student will attain if they consistently answer questions of that level correctly.
/ /
Marks
/Level
2
/ / /2a / (i) 5 miles
(ii) 60 minutes / 2 /
2b / When the line is horizontal, the bus is not moving. It must be at a bus stop. / 2 /
2c / / 3 /
2d / The car passes the bus each time the bus stops and the car’s graph line crosses the bus graph line. This happens twice.
(Note that the places where the lines cross at 30 minutes and 60 minutes are where the bus catches up with and passes the car.) / 3 /
Physics Term 1, Lesson 2 / Marking guide
3
/ / /3a
/ The units of speed are metres per second, m/s. /1
/3b
/ (i) 1000 m(ii) The helicopter has stopped ascending – it is staying at the same height. /
1
2 /3c
/ The slope of the line is the gradient.Average speed of ascent = = 10 m/s /
1
2 /3d
/ (i) Between C and D, the skydiver is being pulled down by gravity and is dropping towards the ground faster and faster.(ii) At point D, the skydiver slows down so their parachute must have opened. /
2
1 /3e
/ In their answers students should be making connections between forces, air resistance, speed and accelerationAward up to four marks for any of the key points.
· Air resistance is caused, as particles of air have to be pushed out
of the way.
· In the first part of the fall, air resistance is increasing because the diver is speeding up and having to push more air out of the way each second.
· In the second part of the fall, just air resistance is constant.
· In the second part of the fall, the air resistance is equal to the weight of the diver. The diver is not accelerating at a constant speed.
· When the parachute opens at D, the air resistance increases and
is much greater than the weight. This means that the diver decelerates.
· During the last part of the fall the speed is constant and so the weight and air resistance are equal again. /
4
/Physics Term 1, Lesson 2 / Marking guide
4 /
4a / Distance travelled and time taken / 2 /
4b / speed = / 2 /
4c / The distance is the same for both James and Asif. One hour is the same as sixty minutes. It takes Asif 60 minutes but it takes James 20 minutes.
So Asif takes = 3 times longer.
So James must run 3 times faster than Asif can walk. / 3 /
4d / The easiest way to show this is to draw an accurate graph.
One line shows Asif walking towards James’s house. It takes him 1 hour (60 minutes).
The other line shows James running towards Asif’s house. It takes him
20 minutes.
Where the two lines cross is the time it takes them to meet. This is
15 minutes. / 1 for correct answer, 2 more for a good method even
if the answer is not correct /