What is the difference between a scalar and a vector quantity?
A scalar has magnitude (size) only. A vector has both magnitude and direction
List three examples of scalar quantities and three examples of vector quantities.
. Scalars: Distance, speed, mass, time, energy.
. Vectors: Displacement, velocity, acceleration, force, momentum.
How is a vector quantity represented on a diagram?
By an arrow. The length represents the magnitude, and the direction of the arrow shows the direction of the quantity.
What is the difference between contact and non-contact forces? Give examples of each.
. Contact: Objects are physically touching (e.g., friction, air resistance, tension).
. Non-contact: Objects are physically separated (e.g., gravity, magnetism, electrostatic force).
According to Newton’s Third Law, what happens when two objects interact?
They exert equal and opposite forces on each other. These forces are the same type and act on different objects.
What is a “resultant force”?
A single force that has the same effect as all the original forces acting on an object combined.
If the resultant force on an object is zero, what can you say about its motion?
It is either stationary or moving at a constant velocity (same speed and direction).
If a non-zero resultant force acts on an object, what happens?
The object will accelerate (change speed, direction, or both).
Define “centre of mass.”
The point at which the mass of an object may be thought to be concentrated.
How do you find the centre of mass of an irregular thin sheet (lamina)?
Suspend the object and a plumb line from a point. Draw the vertical line. Repeat from a different point. The centre of mass is where the lines intersect.
Where does the centre of mass lie for a freely suspended object that has come to rest?
Directly below the point of suspension.
How do you find the resultant of two forces acting at an angle using a scale diagram?
Use the parallelogram of forces method. Draw the two forces to scale, complete the parallelogram, and the resultant is the diagonal starting from the origin.
What does “resolving a force” mean?
Splitting a single force into two components acting at right angles to each other (usually horizontal and vertical).
If an object is in equilibrium, what are the two conditions for the forces acting on it?
- The resultant force is zero.
- The horizontal and vertical components of the forces must balance out.
