What is the definition of acceleration?
Rate of change of velocity over time
Equation: ( a = \frac{v - u}{t} )
What are the units of acceleration?
metres per second squared (m/s²)
Acceleration is a vector quantity.
True or false: Acceleration can occur when the speed changes or when the direction changes.
TRUE
Acceleration can happen even if speed remains constant.
What is the difference between acceleration and deceleration?
- Acceleration: Velocity increases over time
- Deceleration: Velocity decreases over time
Example: A ball thrown upward decelerates due to gravity.
What is the value of acceleration due to gravity on Earth?
9.8 m/s²
This means an object’s velocity increases by 9.8 m/s every second if air resistance is ignored.
Calculate the final velocity using the formula: v = u + at, given u = 2 m/s, a = 2 m/s², t = 4 s.
10 m/s
Calculation: ( v = 2 + (2 × 4) )
Calculate the final velocity for a skydiver given u = 0, a = 9.8 m/s², t = 30 s.
294 m/s
Calculation: ( v = 0 + (9.8 × 30) ) ignoring air resistance.
What does the slope (gradient) of a velocity-time graph represent?
Acceleration
A flat line indicates constant velocity; a sloping line indicates acceleration or deceleration.
Differentiate between mass and weight.
- Mass: Amount of matter (kg)
- Weight: Force of gravity (N)
Mass does not change on the Moon, but weight does.
What is Newton’s First Law?
An object stays at rest or in uniform motion unless acted on by an unbalanced force
Objects with large mass have greater inertia.
What happens when air resistance equals weight during a fall?
Forces are balanced, and acceleration stops
The object then falls at a constant speed, known as terminal velocity.
Calculate the acceleration of a car given F = 3000 N and m = 1200 kg.
2.5 m/s²
Calculation: ( a = \frac{F}{m} )
What is the reaction force when hitting a tennis ball?
Equal and opposite reaction force on the player’s hand
This can cause stress and pain in the wrist.
Calculate the work done lifting a medicine ball given F = 88.2 N and d = 1.2 m.
106 J
Calculation: ( W = F \times d )
What is the formula for Kinetic Energy (Ek)?
E_k = \frac{1}{2}mv^2
Kinetic energy is the energy of motion.
What is the formula for Potential Energy (Ep)?
E_p = mgh
Potential energy is stored energy due to position.
What does the Law of Conservation of Energy state?
Energy cannot be created or destroyed, only transferred or transformed
Total energy before = total energy after.
Why doesn’t a bouncy ball bounce forever?
Some energy is lost as heat, sound, and deformation
Total mechanical energy decreases over time.
Calculate the efficiency given input = 1050 J and useful output = 450 J.
43%
Calculation: Efficiency = \frac{450}{1050} \times 100
Calculate the gravitational potential energy of a 0.5 kg ball dropped from 3 m.
14.7 J
Calculation: ( E_p = mgh = 0.5 \times 9.8 \times 3 )
What is the speed on impact of a ball dropped from 3 m?
7.7 m/s
Calculation: ( v = 7.67 m/s from E_k = \frac{1}{2}mv^2 )
What are balanced forces?
No change in motion (constant speed or stationary)
Opposite forces are equal.
What are unbalanced forces?
Cause acceleration or deceleration
They result in a change in motion.
List the types of energy.
- Kinetic
- Gravitational
- Elastic
- Heat
- Sound
- Chemical
- Light
- Nuclear
These are various forms of energy in physics.
