Forces

• Distance-Time Graphs show how the distance of an object moving in a straight line (from a starting position) varies over time.
• Constant Speed on a Distance-Time Graph is represented by a straight line.
• The slope of the straight line represents the magnitude of the speed: a very steep slope means the object is moving at a large speed, a shallow slope means the object is moving at a small speed, and a horizontal line means the object is stationary (not moving).
• The gradient of a velocity-time graph gives the acceleration for that time period.
• The slope of a velocity-time graph represents the magnitude of acceleration.
• The area under a velocity-time graph represents the displacement, or distance travelled, by an object.
• Objects might be moving at a changing speed, represented by a curve on a Distance-Time Graph.
• If the slope is increasing, the speed is increasing (accelerating), if the slope is decreasing, the speed is decreasing (decelerating).
• The speed of a moving object can be calculated from the gradient of the line on a distance-time graph.
• The car accelerates steadily, so the equation for uniform acceleration can be used: v = u + 2 × a × s.
• The area of an enclosed area under a velocity-time graph represents the total distance travelled.
• If an object moves with constant acceleration, its velocity-time graph will comprise of straight lines.
• The distance travelled by a car during a period of acceleration can be calculated using the equation (v = u + 2as).
• The equation (v = u + 2as) can be used to calculate quantities such as initial or final speed, acceleration, or distance moved in cases where the time taken is not known.
• The gradient of a distance-time graph is equal to the speed of a moving object.
• Time taken is measured in seconds (s)
• Use the stop clock to measure how long the object takes to travel this distance.
• Random Errors: Ensure the experiment is done in a space with no draught or breeze, as this could affect the motion of the falling object.
• The change in velocity is found by the difference between the initial and final velocity, as written below: change in velocity = final velocity − initial velocity Δ v = v − u Where: v = final velocity in metres per second (m/s) u = initial velocity in metres per second (m/s)
• Δ v = change in velocity in metres per second (m/s)
• Acceleration is defined as the rate of change of velocity.
• Consider using an electronic sensor, such as light gates, to obtain highly accurate measurements of time.
• Distance moved is measured in metres (m)
• Systematic Errors: Make sure the measurements on the tape measure or metre rule are taken at eye level to avoid parallax error.
• A steep slope on a velocity-time graph means large acceleration (or deceleration), indicating that the object's speed changes very quickly.
• An object that slows down is decelerating.
• A gentle slope on a velocity-time graph means small acceleration (or deceleration), indicating that the object's speed changes very gradually.
• An object that speeds up is accelerating.
• If an object is speeding up, its acceleration is positive.
• Speed is a scalar quantity because it only contains a magnitude (without a direction).
• If an object is slowing down, its acceleration is negative (sometimes called deceleration).
• The speed of an object is the distance it travels every second.
• A velocity-time graph shows how the velocity of a moving object varies with time.