Assessed Pupil notes Revised Dynamics and Space Done in class National 5 Physics I can describe vector and scalar quantities, and identify them. A scalar quantity has magnitude only A vector quantity has both magnitude and direction. Scalar quantities: speed, distance, mass, time, energy Vector quantities: velocity, displacement, weight, force, acceleration I can calculate the resultant of two vectors Vectors are added “tip-to-tail” The resultant vector is measured from the start of the first vector to the end of the last vector. All resultant vectors must have a three figure bearing, measured from 000˚ (North) National 5 Physics Dynamics and Space Pupil notes I can use a scale diagram or calculation to find a resultant displacement N (000˚) W (270˚) E (090˚) S (180˚) In the above example, the distance travelled is 19km, but to work out displacement, we use a scale drawing. Scale diagram drawing tips: Draw a mini compass. Choose a suitable scale- make it big enough to measure displacement accurately. Write this scale down. - e.g. 1cm:1km Measure your displacement bearing from where you finish, not where you started from (common mistake). To avoid mistakes, quote bearings as a three figure-number. National 5 Physics Dynamics and Space Pupil notes I understand the difference between ‘speed’ and ‘velocity’ 𝑑 =𝑣×𝑡 ‘distance’ and ‘speed’ are scalar quantities and require a magnitude only. where d = distance (measured in metres, m) v = speed (measured in metres per second, ms-1) t = time (measured in seconds, s) 𝑠 =𝑣×𝑡 ‘displacement’ and ‘velocity’ are vector quantities and require both magnitude and direction. where s = displacement (measured in metres, m) and direction v = velocity (measured in metres per second, ms-1) and direction t = time (measured in seconds, s) National 5 Physics Dynamics and Space Pupil notes I know how to get information from velocity-time graphs Car is speeding up (accelerating) from O to A Velocity (ms-1) Car is going at a constant speed from A to B Car is slowing down (decelerating) from B to C Displacement = Area under velocity-time graph I can use the formula which links acceleration, change in speed and time, and calculate acceleration from a velocity-time graph. 𝑎= 𝑣−𝑢 𝑡 𝑎𝑐𝑐𝑒𝑙𝑒𝑟𝑎𝑡𝑖𝑜𝑛 = 𝑐ℎ𝑎𝑛𝑔𝑒 𝑖𝑛 𝑠𝑝𝑒𝑒𝑑 𝑡𝑖𝑚𝑒 where a = acceleration (measured in metres per second squared, ms-2) v = final speed (measured in metres per second, ms-1) u = initial speed (measured in metres per second, ms-1) t = time (measured in seconds, s) National 5 Physics Dynamics and Space Pupil notes I know what is meant by a ‘Force’ A ‘Force’ can change the speed, direction or shape of an object. Force can be measured using a newton balance. Force is measured in Newtons (N). I know that ‘friction’ is a type of force. Friction is caused by two objects moving while in contact with each other. The force of friction is always in the opposite direction to movement. Air resistance and drag are also types of frictional forces. I can describe some ways in which we can reduce frictional forces Streamlining Lubrication Smoothing surfaces National 5 Physics Dynamics and Space Pupil notes I know what is meant by ‘balanced forces’ If two forces are the same size but act in opposite directions, they are known as balanced forces. I understand what Newton’s 1st law tells us about balanced forces and velocity If the forces on an object are balanced, then the object will either stay at rest (not move) or will move with a constant velocity in a straight line. I can calculate the ‘unbalanced force’ if given two different forces in opposite directions I understand what Newton’s 2nd law tells us about unbalanced forces and acceleration. If the forces on an object are unbalanced, then there is more force acting in one direction than the other. The object will accelerate in the direction of the unbalanced force. National 5 Physics Dynamics and Space Pupil notes I can use the formula which links unbalanced force, mass and acceleration 𝐹 =𝑚×𝑎 where Fun = unbalanced force (measured in Newtons, N) m = mass (measured in kilograms, kg) a = acceleration (measured in metres per second squared, ms-2) I can use the formula which links Work done, unbalanced force and distance 𝑊 =𝐹×𝑑 where W = work done, or work energy (measured in Joules, J) F = unbalanced force (measured in Newtons, N) d = distance (measured in metres, m) National 5 Physics Dynamics and Space Pupil notes I know the difference between the mass of an object and its weight Mass is a measure of the amount of ‘stuff’ that makes up an object, and is measured in kilograms. Weight is force acting downwards on an object caused by gravity, and is measured in Newtons. The weight of an object may be different on different bodies in our solar system, but the mass remains the same everywhere. I can use the formula which links weight, mass and gravitational field strength for different objects in our solar system 𝑊 =𝑚×𝑔 where W = Weight (measured in Newtons, N) m = mass (measured in kilograms, kg) g = gravitational field strength (measured in Newtons per kilogram, Nkg-1) National 5 Physics Dynamics and Space Pupil notes I understand what Newton’s 3rd law tells us about action and reaction forces For every ‘action’ (Force) there is an equal and opposite reaction (Force.) ] I understand ‘Free fall’ and ‘Terminal velocity’ in terms of Newton’s laws and Friction. Free fall: Weight of a falling object acts downwards, but there is no ‘reaction force’ acting upwards on the object, giving the sensation of ‘weightlessness.’ Terminal velocity: An accelerating falling object will experience frictional forces which increase until balanced with the object’s weight, which results in a constant speed called terminal velocity. Air Resistance acting upwards No reaction force on diver, so he feels weightless. When air resistance balances weight, terminal velocity is reached. Weight acting downwards National 5 Physics Dynamics and Space Pupil notes I understand what is meant by ‘projectile motion.’ A projectile is an object which is moving only under the influence of gravity, and falls to Earth with a curved path. Projectiles move with a constant horizontal velocity, but accelerate at the same time vertically. Notice how, after each second, the cannonball has travelled the same distance horizontally but travels a greater distance each second vertically. I can perform calculations involving projectile motion from a horizontal launch. From a horizontal launch: v = constant horizontally. u = 0 ms-1 vertically. a = 9.8 ms-2 vertically downwards. Top tip: split your page in two down the middle one side for horizontal motion the other for vertical motion. Horizontal Vertical d = 100m a = 9.8 ms-1 v = 10 ms-1 v =? t=? u = 0 ms-1 t =? National 5 Physics Dynamics and Space Pupil notes I can explain the orbit of a satellite in terms of projectile motion A satellite, after launch, will begin to fall towards earth with a curved path, just like any projectile. If launched with enough velocity, the curved path will extend beyond the curvature of the earth, and the satellite will continue to follow that curved path around the earth. This is how a satellite stays in orbit. I can describe some of the risks and benefits of space exploration Risks Re-entry to a planet’s atmosphere is challenging because It creates a large amount of heat due to air resistance. Thermal protection systems must be used to ensure the spacecraft is protected on re-entry. The angle of re-entry must be precisely calculated so the spacecraft doesn’t ‘bounce off’ the atmosphere. Benefits Space exploration has helped to develop The accuracy of weather forecasting Telecommunications via Satellites Analysis of our environment National security Sat-Nav systems Robotics National 5 Physics Dynamics and Space Pupil notes I can discuss the impact that space exploration has had on our understanding of the universe and of planet Earth Space telescopes (e.g. Hubble), Space probes (e.g. Voyager) and Space rovers (e.g. Spirit) have all contributed to our understanding of the universe in different ways. For example: Hubble’s deep field lens allows us to capture images across many wavelengths of EM radiation from deep space. Voyager has performed ‘fly pasts’ of many objects in our solar system giving up close, detailed images never seen before. Spirit analysed the terrain on Mars to help determine if life had ever existed there. I know that large distances in space are measured in light years. A light year is the distance that light will travel in one year: One light year = 9.5 x1015 metres. Our solar system measures only a small fraction of a light year, yet the universe measures many billions of light years. National 5 Physics Dynamics and Space Pupil notes I know what is meant by the ‘observable universe’ and what it tells us about the origin and age of the universe Since light travels at a finite speed, it takes some time to get to us. If an object is far enough away, its light may not have reached us yet. The furthest point that we can ‘see’ is the distance which light must have travelled for the whole age of the universe. This distance is called the ‘observable universe.’ This means that we can calculate the age of the universe- estimated to be just less than 14 billion years old. The universe is constantly expanding- objects are getting further apart. This suggests that all matter in the universe has all been expanding from a single point- an expansion started by the big bang. I know that different objects in the universe can be detected using different parts of the electromagnetic spectrum. Some objects in the universe cannot be detected using ‘visible’ light, and look dark when viewed with optical telescopes. However, these objects often emit radiation in the form of Infrared, Ultraviolet, X-rays or gamma rays, which can be detected by using specialised telescopes. National 5 Physics Dynamics and Space Pupil notes I can identify a continuous spectrum and a line spectrum White light sources, when ‘split up’ using a prism or viewed through a spectroscope will produce a ‘continuous spectrum’ of colours (ROY G BIV). Other light sources (such as fluorescent ‘strip’ lamps) will instead produce a ‘line spectrum’ when viewed through a spectroscope, where not all the colours are present. NB: One of these is called a ‘spectrum’ and more than one of these are called ‘spectra’. I can use ‘line spectra’ to identify the elements present in stars Different elements emit different wavelengths (colours) of light depending on their atomic structure. These act as an ‘atomic fingerprint’ that can identify the element. Looking at light coming from a star using a spectroscope will identify the elements in that star. The line spectrum for Hydrogen