To conclude the recent series of posts related to different aspects of motion, we will now look at a real-world application of these ideas: in particular, the physics of slowing and stopping a road vehicle. An earlier post (from 2019) covered the two components of a vehicle’s overall stopping distance so I won’t repeat that … Continue reading Slowing and Stopping
Momentum
Newton's Second Law of Motion tells us that the force required to accelerate an object can be calculated by multiplying the mass of the object by the acceleration that is required (F=ma). We also know that acceleration is simply the rate of change of velocity (the change in velocity divided by the time taken for … Continue reading Momentum
Force and Acceleration
There are various techniques that can be used to investigate the relationship between force, mass and acceleration (Newton’s Second Law of Motion). In a school lab, we often use a dynamics trolley (wheeled platform) that is attached to a mass hanger via a string that runs over a desk pulley. The mass hanger provides the … Continue reading Force and Acceleration
Forces and Motion
Let’s get the common misconception out of the way first: moving objects do not remain in motion because there is a force that keeps them going. In fact, it’s the opposite. Moving objects always remain in the same state of motion unless an external force stops them. By “the same state of motion” we mean … Continue reading Forces and Motion
Acceleration and Distance
To find acceleration without measuring time, we can use a combination of the object's mean speed and distance-moved as a substitute for time. We already know that speed is calculated as distance divided by time, so we can rearrange this equation to calculate time as distance divided by speed. Of course, the speed of an … Continue reading Acceleration and Distance
Calculating Acceleration
Acceleration is the rate of change of speed (we will leave aside velocity for now) and that means we can calculate acceleration if we know the speed of an object at two different times. The object’s acceleration is given by its change in speed, divided by the time interval. Positive acceleration indicates that the object … Continue reading Calculating Acceleration
Measuring Speed
This is the third part of a mini-series looking at motion and here we’ll be considering different ways to measure speed as well as some common sources of error. In theory, speed is easy; we just need a distance (measured using a ruler, for example) and a time (probably measured using a stopwatch but ideally … Continue reading Measuring Speed
Speed and Acceleration
When a stationary object starts moving in a straight line, its motion can be divided into two stages. The first stage is when the speed of the object is increasing; the second stage is when the object has reached a steady speed. We can rephrase these two stages using the word acceleration; the first stage … Continue reading Speed and Acceleration
Speed and Velocity
In many situations, the word “speed” is used when in fact “velocity” would sometimes be more appropriate. Speed is the rate of change of distance: the word “rate” indicates time, so speed is simply a measure of how much the distance changes in each second of movement. If you took 80 seconds to run 400 … Continue reading Speed and Velocity
Molar Heat Capacity
There is a required practical in GCSE Physics courses, including Trilogy, that involves calculating the specific heat capacity of different metal blocks. This is done by measuring the energy supplied (using voltage, current and time) and monitoring the temperature increase. You are expected to recall this experiment and be able to suggest how it could … Continue reading Molar Heat Capacity
Mr Tarrant's physbang 'blog 