Télécharger la présentation
## Newtons law

- - - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - - -

**Newtons law**• In this section you will • be introduced to Newton’s second law of • motion • look at how Newton’s law can be investigated • use the equation to solve problems**Newtons law**Isaac Newton said that:- An object will remain stationary or move at a unless a resultant acts on it.**Newtons law**Isaac Newton said that:- An object will remain stationary or move at a constant velocity unless a resultant force acts on it.**EXPERIMENT 1**The air track removes the force of friction. The only force will be exerted by the weights. You will see how increasing the force on the glider affects it’s acceleration**Investigating Newton’s law**GLIDER Bench Bench 2**Investigating Newton’s law**GLIDER Bench Bench 2**Investigating Newton’s law**GLIDER Bench Bench 2**Investigating Newton’s law**GLIDER Bench Bench 2**Force**GLIDER Bench 10g Mass holder Bench Weight 2 Fill in the missing numbers To show you understand the pattern (trend) Click to check your answers**Force**GLIDER Bench 10g Mass holder Bench Weight 2**EXPERIMENT 2**The air track removes the force of friction. The only force will be exerted by the weights. You will see how increasing the mass of the glider affects it’s acceleration**Investigating Newton’s law**GLIDER Bench Bench 2**Investigating Newton’s law**GLIDER Bench Bench 2**Investigating Newton’s law**GLIDER Bench Bench 2**Investigating Newton’s law**GLIDER Bench Bench 2**Investigating Newton’s law**GLIDER Bench Bench 2**Force**GLIDER Bench 10g Mass holder Bench Weight 2 Click to check your answers Fill in the missing numbers To show you understand the pattern (trend)**Force**GLIDER Bench 10g Mass holder Bench Weight 2**Force**GLIDER Bench 10g Mass holder Bench Weight 2 2**Summary**More force on the glider causes acceleration. If the mass of the glider is the acceleration is reduced These results are summarised by the equation force = mass x acceleration F = m x a Complete the Missing words Click to see answers (N) (m/s ) 2 (kg)**Summary**More force on the glider causes more acceleration. If the mass of the glider is increased the acceleration is reduced These results are summarised by the equation Resultant force = mass x acceleration F = m x a (N) (m/s ) 2 (kg)**Questions**1 A car has a thrust of 1200N and a mass of 800kg. Work out it’s acceleration a = = 2 A car brakes with a force of 800N and has a deceleration of 2m/s . Work out the mass of this car. 3 A car of mass 500kg accelerates at 1.5m/s work out the thrust force of the engine 4 A car with a thrust of 1000N has a mass of 800kg. If the drag force is 200N work out the acceleration. Click to see answers : 2 m = = : 2 F = X = a = = :**Questions**1 A car has a thrust of 1200N and a mass of 800kg. Work out it’s acceleration 2 A car brakes with a force of 800N and has a deceleration of 2m/s . Work out the mass of this car. 3 A car of mass 500kg accelerates at 1.5m/s work out the thrust force of the engine 4 A car with a thrust of 1000N has a mass of 800kg. If the drag force is 200N work out the acceleration. a = 1200N/800kg = 1.5m/s 2 2 m = 800N/2m/s = 400kg 2 2 2 F = 500N X 1.5m/s = 750N 2 a = (1000 – 200)/800 = 800/800=1m/s**No drag**force Mass of person = 70kg Work out the accelerations 2 2 2 2 a = = m/s a = = m/s a = = m/s a = = m/s 210 N 490 N 700 N A TERMINAL VELOCITY B C 700 N D 700 N Gravity Air friction 700 N 700 N Equation to use is a=F/m (where F is the resultant force) A C B D Click to see answers**No drag**force Mass of person = 70kg Work out the accelerations 210 N 490 N 700 N A TERMINAL VELOCITY B C 700 N D 700 N Answers A = 10m/s B = 7m/s C = 3m/s D = 0m/s (terminal velocity) 2 2 700 N 700 N 2 2