Motion, Forces and Energy

What is the purpose of a ruler in measurements?

To measure length by placing the object starting from the 0 mark and reading the scale at eye level.

How is the volume of an irregular object measured?

Volume = final water level - initial water level (using a measuring cylinder).

What is the formula for calculating speed?

speed = distance / time.

What is the difference between speed and velocity?

Speed is distance travelled per unit time, while velocity is speed in a given direction (a vector).

What does the gradient of a distance-time graph represent?

The speed of the object.

What indicates that an object is at rest in a distance-time graph?

A flat horizontal line.

What is acceleration?

The change in velocity per unit time.

What is the equation for acceleration?

acceleration = change in velocity / time taken.

What is terminal velocity?

The constant speed an object reaches when the force of air resistance equals its weight.

What is the weight of an object?

The force of gravity acting on a mass, measured in newtons (N).

How is weight calculated?

weight = mass × gravitational field strength (W = m × g).

What is density?

The mass per unit volume of an object.

What is the formula for density?

density = mass / volume (ρ = m / V).

What determines if an object will float in a fluid?

An object will float if its density is less than the density of the fluid.

What does Hooke's Law state?

The extension of a spring is directly proportional to the force applied until the limit of proportionality is reached.

What is the principle of moments?

For a body to be balanced, the total clockwise moment about a pivot must equal the total anticlockwise moment.

What is momentum?

The product of mass and velocity; it is a vector quantity.

What is the equation for momentum?

momentum = mass × velocity (p = m × v).

What is the principle of conservation of momentum?

In a closed system, the total momentum before a collision equals the total momentum after the collision.

What type of energy is kinetic energy?

The energy an object has due to its motion.

What is the formula for kinetic energy?

Eₖ = ½ × m × v².

What does the principle of conservation of energy state?

Energy cannot be created or destroyed, only transferred from one store to another.

What is work done?

The energy transferred when a force moves an object.

What is the equation for work done?

work done = force × distance moved in the direction of the force (W = F × d).

What is power?

The rate of doing work or transferring energy.

What is the equation for power?

power = work done / time taken (P = W / t).

What is pressure?

The force exerted per unit area.

What is the equation for pressure?

pressure = force / area (p = F / A).

How does pressure change in liquids?

Pressure increases with depth and with the density of the liquid.

What is the equation for calculating pressure in a liquid?

pressure = density × g × height (p = ρ × g × h).

What is the effect of increasing the area on pressure?

Increasing the area reduces pressure.

What happens when the area is decreased?

Pressure increases.

What is average speed?

Total distance travelled divided by total time taken.

What indicates constant speed on a distance-time graph?

A straight sloping line.

What does a curved line on a distance-time graph indicate?

Acceleration (increasing gradient) or deceleration (decreasing gradient).

What is deceleration?

Negative acceleration.

How is the resultant of two vectors at right angles found?

Using Pythagoras' theorem.

What can forces change about an object?

An object's shape, speed, or direction of motion.

What determines the center of gravity of an object?

The point where its entire weight appears to act.

How can the center of gravity of an irregular shape be found?

Suspend it and draw lines along a plumb line from two different points.

What makes an object stable?

A low center of gravity and a wide base.

How can density be determined for a regular solid?

Measure its mass and calculate volume (e.g., length × width × height).

What happens to objects falling without air resistance?

They fall with the same constant acceleration of 9.8 m/s².

What is the gravitational field strength on Earth?

Approximately 9.8 N/kg.

What do clocks or digital timers measure?

Time.

What is measured using a measuring cylinder?

Volume.

What should be done to time short events accurately?

Measure multiple events and find the average.

What is mass?

The amount of matter in an object.

Is mass the same everywhere?

Yes, mass is the same regardless of location.

In what units is mass measured?

Kilograms (kg).

What is the relationship between weight and mass?

Weight is the force of gravity acting on a mass.

What happens when air resistance equals an object's weight?

The object reaches terminal velocity and falls at a constant speed.

What does the slope of a speed-time graph represent?

The acceleration of the object.

What does the area under a speed-time graph represent?

The distance travelled.

What is the definition of impulse?

The change in momentum, calculated as force multiplied by time.

What influences the density of a liquid?

The mass of the liquid and its volume.

What are renewable energy resources?

Energy resources that will not run out, such as solar, wind, and hydroelectric.

What is efficiency?

The ratio of useful energy output to total energy input.

What is the formula for efficiency?

% Efficiency = (useful energy out / total energy in) × 100%.

What is the effect of a flat horizontal line on a speed-time graph?

It indicates constant speed with acceleration of zero.

How does an object behave when in equilibrium?

The resultant force and moment are both zero.

What are the two types of quantities in physics?

Scalar quantities (e.g., mass, speed) and vector quantities (e.g., force, velocity).

What is Hooke's Law's equation?

F = k × x, where F is force, k is the spring constant, and x is extension.

What does it mean if the resultant of two forces is zero?

The object is in equilibrium and will not accelerate.

What does a straight sloping line indicate in a speed-time graph?

Constant acceleration.

What indicates that an object is accelerating in a speed-time graph?

A sloping line upwards.

What is the acceleration of free fall near Earth?

Approximately 9.8 m/s².

What type of quantity is energy?