11R1 Exam Revision LO: To review the topics for the February exam. Thursday, 23 May 2019 Calculations involving percentages: Calculate 2% of 50 g. Calculate 2% of 0.025 kg. Calculate the percentage of people who are above 6ft if 7 out of 19 people are. Calculate the total number of people if 3% of people are represented by 9 people. Calculate the percentage equivalent of 15 out of 329.27. S & C: Calculate the total number if 3% represents by 9.235.

Plotting Data

Determining uncertainty in data

Standard Form Calculations involving standard form: 1.2 x 103  1,200 1.2 x 10-3  0.0012 Calculations involving standard form: Calculate 2.35 x 107. Calculate 2.35 x 10-1. Rewrite in standard form 1,000,000. Rewrite in standard form 8,987,325. Calculate 7.865 x 10-6. S & C: Rewrite in standard form 0.005678.

Rearranging equations Rearrange A = B x C to make C the subject. Rearrange A/B = C to make A the subject. Rearrange A/B = C to make B the subject. Rearrange Energy = mass x SHC x temp. ch. to make SHC the subject. Rearrange KE = ½ x mass x velocity2 to make V the subject.

Forces To log on to Doddle: Institution: Ralph Thoresby   Institution: Ralph Thoresby Username: fullname14 (the year you started Y7) Password: ralph

Forces Scalar & Vector Quantities Contact & Non-Contact Forces Gravity & Weight Resultant Forces Work Done & Energy Transfers Elasticity (Force & PE) Distance & Displacement Speed Velocity DT Graphs Acceleration VT Graphs Newton I – III Stopping Distance – Thinking Distance & Braking Distance Momentum

Scalar & Vectors

The larger the arrow, the larger the force. Forces are pushes, pulls or turning forces acting on objects…measured in Newtons (N) The larger the arrow, the larger the force. Unbalanced (resultant) forces changes speed, direction or both (velocity)… Reaction force Tension Lift Draw forces from centre of object Upthrust Reaction Gravity

g = 10N/kg on Earth… E.g. Mass = 70kg g = 1.5N/kg Weight = ? Weight = 70 x 1.5 = 105 N

Work Done = Force x Distance The force in a vertical direction = weight (mass x g) J N m Effort, but no work done (with respect to holding the books) W.D. = 50 x 12 = 600 J No movement in the direction of the force, then no work done. Work done Example 2 g = 10N/kg Work done Example 3 A climber has a weight of 800N and climbs up 50m. What is the work done? Clue! Weight = force W.D. = 800 x 50 = 40,000 J Clue! Mass does not equal force… W.D. = (55 + 2) x 10 x 5 = 2850 J

Distance-Time (DT) Graphs Speed = Distance = Change in Y = Gradient Time Change in X

Velocity-Time (VT) Graphs Acceleration = Velocity = Change in Y = Gradient Time Change in X

Springs store elastic potential energy… Hooke's Law F = k × e F is the force in newtons, N k is the 'spring constant' in newtons per metre, N/m e is the extension in metres, m An elastic object such as a spring stores elastic potential energy when stretched or squashed. The extension of an elastic object is directly proportional to the force applied. Potential Energy

Newton’s Laws of Motion Newton’s First Law Newton’s Second Law Newton’s Third Law

stopping distance = thinking distance + braking distance

Momentum Kg m/s kg m/s Momentum = Mass x Velocity Momentum before = Momentum after

Forces Learning Check What is the unit of force? What is a resultant force and what does it do? Draw the forces on a ball speeding up as it falls. Draw the forces on an aeroplane in steady flight. Resolve the forces for a stone shoved off a cliff with a horizontal force of 20N if gravity is 10N (assume no air resistance). Newtons (N) Overall force. Changes speed, direction or both (changes velocity). On next slide

Springs Learning Check What is Hooke’s law? What do we mean by ‘spring extension’? A spring is stretched by 5cm by a weight. How much will two springs fastened side by side be stretched by? Calculate the force need to stretch a spring by 20cm if the spring constant is 2N/m. Calculate the energy stored in the same spring if stretched to 30cm. F = k e (‘stretch’ is proportional to applied force). The amount of stretch/increase in length. 2.5cm for two side-by-side springs. F = k e 20cm = 0.2m = 2 x 0.2 = 0.4N Energy = 0.5 k x2 30cm = 0.3m. = 0.5 x 2 x 0.32 = 0.09J

Work Done (W.D.) Learning Check What is the equation for work done? What is the work done for a force of 50N moving 50cm. Calculate W.D. for a climber of weight 300N climbing up 5m of rock. Calculate W.D. for a climber of mass 50kg (g = 10N/kg) climbing 75cm vertically. Calculate the W.D. for a person holding 20kg of books for 10 minutes. W.D. = force x distance W.D. = f d = 50x0.5 = 25J W.D. = 300x5 = 1500J W.D. = 50x10x0.75 = 350J Zero, as no movement mentioned.

Waves To log on to Doddle: Institution: Ralph Thoresby   Institution: Ralph Thoresby Username: fullname14 (the year you started Y7) Password: ralph

Waves Transverse & Longitudinal Waves (Labelling) Wave Equation & Period EM Spectrum (Uses & Dangers) Radio Waves & Aerials

Transverse & Longitudinal Waves Transverse Wave

Refraction Part of a wavefront enters the water (or any denser material like glass) and slows down while the rest of the wavefront stays at the same speed and angle…

Wave Speed = Frequency x Wavelength Wave Equation & Period Period = 1/Frequency Wave Speed = Frequency x Wavelength m/s Hz m Example 2: Wave speed = 2m/s, frequency = 0.5Hz. What is the wavelength? 2 = 0.5 x ?  2/0.5 = ? = 4m

EM Spectrum (Uses & Dangers) Microwaves Infrared UV X-rays Gamma rays Internal tissue heating Skin burns Ionising radiation so can cause cancer in low doses and kill cells in high doses.

Radio Waves & Aerials

Magnetism & Electromagnetism To log on to Doddle:   Institution: Ralph Thoresby Username: fullname14 (the year you started Y7) Password: ralph

Magnetism & Electromagnetism Magnetic Poles & Fields (Bar & Solenoid) Electromagnets (Variables & Uses) Fleming’s LHR Electric Motor & Fleming’s LHR

Magnetic Poles & Fields (Bar & Solenoid) Bar magnet Solenoid

Electromagnets (Variables & Uses) What affects the strength of an electromagnet? Or a higher current!

Fleming’s LHR

Electric Motor & Fleming’s LHR 2. 1. 3. Can you apply the rule to each situation to get the same result?