What is acceleration?
Acceleration is the rate of change of velocity. It can occur when an object speeds up, slows down, or changes direction.
What are the SI units for velocity, acceleration, and force?
Velocity: m/s (meters per second)
Acceleration: m/s² (meters per second squared)
Force: N (Newtons)
What is the difference between speed and velocity?
Speed is distance traveled ÷ time taken regardless of direction. Velocity is speed in a given direction.
What is the formula for acceleration?
a = Δv/t or a = (v - u)/t
Where:
a = acceleration
Δv = change in velocity
v = final velocity
u = initial velocity
t = time
What does deceleration mean?
Deceleration is negative acceleration - when an object slows down. The acceleration value is negative.
State Newton’s First Law
If the resultant force acting on an object is zero:
A moving object will continue to move at the same velocity
A stationary object will remain at rest
State Newton’s Second Law
The relationship between resultant force, mass, and acceleration is:
F = m × a
Where:
F = force (N)
m = mass (kg)
a = acceleration (m/s²)
State Newton’s Third Law
Whenever two objects interact, the forces they exert on each other are equal in magnitude and opposite in direction.
What is a resultant force?
A single force that has the same effect on motion as all the original forces acting together.
What happens when there is a non-zero resultant force?
The object will accelerate in the direction of the resultant force.
What happens when the resultant force is zero?
The object maintains constant velocity (including zero velocity if at rest).
What does the gradient of a velocity-time graph represent?
The gradient equals the acceleration of the object.
How do you calculate acceleration from a velocity-time graph?
acceleration = gradient = rise/run = change in velocity ÷ change in time
What do different line shapes mean on a velocity-time graph?
- Positive gradient: increasing velocity (acceleration)
- Zero gradient (horizontal line): constant velocity
- Negative gradient: decreasing velocity (deceleration)
What does the area under a velocity-time graph represent?
The displacement (distance traveled) by the object.
How do you calculate distance from a velocity-time graph?
Calculate the area under the line using geometry (triangles, rectangles) or by counting squares.
How are force and acceleration related?
Force is directly proportional to acceleration (F ∝ a). Larger force = larger acceleration.
How are mass and acceleration related?
Acceleration is inversely proportional to mass (a ∝ 1/m). Larger mass = smaller acceleration for the same force.
Which trolley will have the smallest acceleration if the same force is applied to trolleys of different masses?
The trolley with the largest mass will have the smallest acceleration.
Why does a baseball accelerate quickly when hit?
The baseball experiences a large resultant force from the bat, causing rapid acceleration due to Newton’s Second Law.
When does a car decelerate?
When slowing down (e.g., leaving a motorway), the resultant force acts opposite to the direction of motion.
When is a car’s acceleration zero?
When traveling at constant velocity (no change in speed or direction).
Calculate: A car accelerates from 10 m/s to 30 m/s in 5 s. What is its acceleration?
a = (v - u)/t = (30 - 10)/5 = 4 m/s²
Calculate: An object of mass 4 kg has acceleration 3 m/s². What is the resultant force?
F = ma = 4 × 3 = 12 N
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Unit 1 - Forces and interactions56
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1.1.2 Scalar and Vector Quantities13
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1.1.4 Mass and Weight15
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1.1.5 Elasticity16
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Unit 2 - Motion34
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Unit 3 - Resultant Force30
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Unit 4 - Momentum32
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Unit 5 - Safety in Public Transport13
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Unit 6 - Terminal Velocity18
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Unit 7 - Center of Mass14
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Unit 8 - Moments and Levers12
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Exam 35
