Unit notes and practice questions
Everything here is for unit 2 of the Grade 10 Physics textbook: what the chapter covers, the short notes, practice questions with their answers, and the lesson video where one exists.
The cards filed under this chapter on the Grade 10 Physics page. Open one at a time.
When you use it
Reach for this distinction when a question asks about slowing down or motion in negative coordinates.
Watch out
Deceleration always reduces speed because acceleration is opposite to velocity. Negative acceleration only means pointing in the negative coordinate direction and can increase speed if velocity is also negative.
Drafted from Grade 10 Physics, pages 28-59, then checked twice before it went up
When you use it
Use when calculating displacement of an object moving with uniform acceleration over a known time interval.
Watch out
Acceleration must be constant throughout the motion. In free fall without air resistance, acceleration equals g.
Drafted from Grade 10 Physics, pages 28-59, then checked twice before it went up
| Graph Type | Slope | Area Under Curve |
|---|---|---|
| Position-time () | Velocity | No physical meaning |
| Velocity-time () | Acceleration | Displacement |
| Acceleration-time () | No physical meaning | Change in velocity |
When you use it
Use to identify physical quantities represented by slopes and enclosed areas on motion graphs.
Watch out
The area under a velocity-time graph yields displacement, which is not always equal to total distance.
Drafted from Grade 10 Physics, pages 28-59, then checked twice before it went up
When you use it
Use to determine the velocity of body A as observed from the reference frame of moving body B.
Watch out
Direction signs are critical: if objects move toward each other, assign one direction as positive and the opposite as negative.
Drafted from Grade 10 Physics, pages 28-59, then checked twice before it went up
When you use it
Use to find the velocity of an object after it accelerates at a constant rate for time t.
Watch out
When an object slows down, acceleration has the opposite algebraic sign to velocity.
Drafted from Grade 10 Physics, pages 28-59, then checked twice before it went up
10 multiple-choice questions written against this chapter, each with its answer and the reason. Try one before you open the answer.
Question 1
A student walks 200 m east from home to a shop, then walks the same way back. What is the displacement for the whole trip?
Answer: C Zero
Why
Displacement is the change in position, measured straight from start to finish. The student finishes exactly where they started, so the displacement is zero. Option A is the distance travelled, which is 400 m, and distance is the quantity that can never come back to zero once you have moved.
Question 2
A car speeds up from 10 m/s to 30 m/s in 4 s. What is its acceleration?
Answer: B 5 m/s²
Why
Acceleration is the change in velocity divided by the time: a = (30 - 10) / 4 = 20 / 4 = 5 m/s². Option C comes from dividing the final velocity by the time instead of the change in velocity.
Question 3
A stone is dropped from rest and falls for 3 s. How far does it fall?
Answer: C 45 m
Why
Dropped means the initial velocity is zero, so s = ut + (1/2)at² becomes s = (1/2)(10)(3²) = (1/2)(10)(9) = 45 m. Option B is what you get by using v = u + at, which gives the final speed of 30 m/s rather than a distance.
Question 4
Which equation of motion would you use when the question never mentions time?
Answer: C v² = u² + 2as
Why
Each equation leaves out one quantity. v² = u² + 2as is the only one with no t in it, so it is the one to reach for when time is neither given nor asked for. Every other option contains t.
Question 5
A driver travelling at 20 m/s brakes at 4 m/s². How far does the car travel before it stops?
Answer: C 50 m
Why
Time is not mentioned, so use v² = u² + 2as with v = 0 and a = -4 m/s², because the acceleration opposes the motion. Then 0 = 400 + 2(-4)s, so 8s = 400 and s = 50 m. Option A is what you get by finding the stopping time, 5 s, and reporting it as a distance.
Question 6
On a velocity against time graph, what does the area under the line represent?
Answer: B Displacement
Why
Velocity multiplied by time gives displacement, and that product is exactly what the area represents. The slope of the same graph gives acceleration, which is why option A is the common wrong choice.
Question 7
A ball is thrown straight upward. At the highest point of its flight, what are its velocity and acceleration?
Answer: B Velocity zero, acceleration 10 m/s² downward
Why
At the top the ball has stopped rising and has not yet started falling, so its velocity is zero for that instant. Gravity never switches off, so the acceleration is still 10 m/s² downward, which is what starts the ball moving down again. Option A is the most common wrong answer, and it would mean the ball hangs there forever.
Question 8
A bus travelling at 72 km/h needs its speed in metres per second. What is it?
Answer: B 20 m/s
Why
Divide by 3.6 to convert km/h into m/s: 72 / 3.6 = 20 m/s. The conversion comes from 1000 metres per kilometre divided by 3600 seconds per hour. Option D multiplies by 3.6 instead of dividing.
Question 9
Two buses travel along the same road in opposite directions, one at 60 km/h and the other at 50 km/h. What is the magnitude of their relative velocity?
Answer: C 110 km/h
Why
Taking one direction as positive, the second bus has a velocity of -50 km/h. Relative velocity is 60 - (-50) = 110 km/h. Option A would be right only if they were travelling the same way, which is why the sign matters so much in these questions.
Question 10
A minibus starts from rest and accelerates uniformly, reaching 24 m/s after 6 s. How far does it travel in that time?
Answer: B 72 m
Why
Both velocities and the time are known, so use s = ((u + v) / 2)t = ((0 + 24) / 2) x 6 = 12 x 6 = 72 m. Option C comes from multiplying the final velocity by the time, which would only be right if the bus had travelled at 24 m/s the whole way.
Unit 2 runs from page 28 to page 59 of the Ministry of Education edition.
Ministry of Education edition, English, 212 pages
Temari turns this chapter into timed practice and marks it as you go, with an AI tutor to explain anything that did not land.
Start free
Temari.et is also an Android app, free on Google Play.
