Unit notes and practice questions
Everything here is for unit 1 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
When combining two or more vectors to determine their resultant magnitude.
Watch out
Never add vector magnitudes by simple scalar addition unless both vectors are parallel and point in the same direction.
Drafted from Grade 10 Physics, pages 6-27, then checked twice before it went up
When you use it
When determining whether a given set of vectors can sum to a zero vector.
Watch out
Two vectors can produce a zero resultant only if they have equal magnitude and opposite directions. Three vectors of unequal magnitude can also sum to zero.
Drafted from Grade 10 Physics, pages 6-27, then checked twice before it went up
When you use it
Use this to find the directional angle of a resultant vector from its horizontal and vertical components.
Watch out
State the reference direction explicitly such as north of east or south of west, not just the angle value.
Drafted from Grade 10 Physics, pages 6-27, then checked twice before it went up
When you use it
Use this formula to calculate the magnitude of the resultant vector when two vectors act at a right angle to each other.
Watch out
This equation applies only when the angle between the two vectors is exactly 90 degrees.
Drafted from Grade 10 Physics, pages 6-27, then checked twice before it went up
When you use it
Use this to resolve a single vector into its perpendicular horizontal and vertical components.
Watch out
Ensure the angle is measured from the horizontal axis. If measured from the vertical, cosine and sine swap roles.
Drafted from Grade 10 Physics, pages 6-27, 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
Which of the following physical quantities is a vector quantity?
Answer: D Weight
Why
According to the textbook, weight, force, and velocity are vectors because they have both magnitude and direction. Volume, temperature, and mass are scalar quantities because they have magnitude only.
Question 2
What is the resultant magnitude when two parallel vectors A = 6.8 cm and B = 5.5 cm act in the same direction?
Answer: B 12.3 cm
Why
When two vectors point in the same direction, their resultant is found by direct addition: R = A + B = 6.8 cm + 5.5 cm = 12.3 cm.
Question 3
What is the name of the single vector that produces the same overall effect as two or more vectors added together?
Answer: C Resultant vector
Why
The resultant vector is the result of adding two or more vectors together. The individual vectors can be replaced by the resultant where the overall effect is the same.
Question 4
Under what condition can the sum of two vectors be equal to zero?
Answer: D When they have equal magnitudes and point in opposite directions
Why
The sum of two vectors can only be zero if they are equal in magnitude and opposite in direction.
Question 5
A force F = 40 N acts at an angle of 30° to the horizontal. What is the vertical component (Fy) of this force? (Note: sin 30° = 0.5)
Answer: A 20 N
Why
The vertical component is calculated as Fy = F sin θ = 40 N × sin 30° = 40 N × 0.5 = 20 N.
Question 6
An athlete in Hawassa runs 6 m north and then 8 m east. What is the magnitude of the athlete's resultant displacement?
Answer: C 10 m
Why
Since north and east are perpendicular, we use Pythagoras' theorem: R = √(62 + 82) = √(36 + 64) = √100 = 10 m.
Question 7
In the parallelogram law of vector addition, two vectors are joined tail to tail. Which part of the parallelogram represents their resultant vector?
Answer: B The diagonal of the parallelogram
Why
When two vectors form the adjacent sides of a parallelogram by joining their tails, the sum of the two vectors is given by the diagonal of the parallelogram.
Question 8
A displacement vector has a magnitude of 2.0 m directed due east. What is the magnitude of its component along the north direction?
Answer: C 0.0 m
Why
A vector that points completely along the east direction (x-axis) has no vertical part. Therefore, its component along the north direction (y-axis) is 0.0 m.
Question 9
A force vector of 10 N acts in the positive x direction. Which pair of forces acting in the negative x direction will result in a net force of zero?
Answer: B 4 N and 6 N
Why
For the resultant to be zero, the total force in the negative x direction must equal 10 N. The forces 4 N and 6 N add up to 10 N in the negative direction, canceling out the 10 N positive force.
Question 10
According to the polygon law of vector addition, if several vectors are represented by consecutive sides of a polygon taken in order, how is their resultant represented?
Answer: A By the closing side of the polygon taken in the opposite order
Why
The polygon law states that if a number of vectors are represented in magnitude and direction by the sides of a polygon taken in the same order, then their resultant is represented in magnitude and direction by the closing side of the polygon taken in the opposite order.
The app holds 12 questions on this unit, marked as you go. These are the first 10.
Unit 1 runs from page 6 to page 27 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.
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