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Motion

Motion. Physics 201 2014. Forces and motion. When a force acts on an object, the object will accelerate. This is how we have the equation F res = ma F = Force (N) m = mass (g) a = acceleration (ms -2 )

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Motion

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  1. Motion Physics 201 2014

  2. Forces and motion When a force acts on an object, the object will accelerate. This is how we have the equation Fres = ma F = Force (N) m = mass (g) a = acceleration (ms-2) Gravitational attraction on Earth causes all objects to have a weight force due to the acceleration of gravity giving us the variation Fw = mg

  3. Forces review Draw the following forces acting on the objects below. Remember force is a vector…

  4. Forces we should know • Thrust • Friction • Air resistance • Water resistance • Drag • Weight • Gravity • Support/upthrust

  5. Mass, Weight, and Terminal Velocity • Mass is the amount of matter in an object, it is measured in kilograms (kg). Weight is the force due to gravity. • The mass of an object remains constant wherever it is. The weight of an object depends on the mass of the object and the strength of gravity where the object is. On Earth it acts downwards, towards the centre of the Earth. • Weight = mass x g (On Earth g = 10 ms–2) Terminal velocity

  6. Terminal Velocity and the parachute 

  7. Newton's Laws of Motion Newton’s first law: An object at rest will remain at rest unless acted on by an unbalanced force. An object in motion continues in motion with the same speed and in the same direction unless acted upon by an unbalanced force. This law is often called "the law of inertia”. Use the equation Fres = ma to calculate

  8. Newton’s First Law The 2014 Russian Men's 2 Man bobsled team won gold at the winter Olympics. The sled was stationary until Alexey begin to push it. While the sled is stationary there is no acceleration, therefore there is no force.

  9. Newton’s First Law, continued… Alexander (in the front) is sitting on the sled and together have a mass of 200kg. Alexey’s job is to run and jump into the sled. Alexey accelerates at a magnitude of 1.52ms-2. Calculate how much Force Alexander and the sled will have when Alexey begins to push.

  10. Newton’s First Law, continued… Alexander (in the front) is sitting on the sled and together have a mass of 200kg. Alexey’s job is to run and jump into the sled. Alexey accelerates at a magnitude of 1.52ms-2. Calculate how much Force Alexander and the sled will have when Alexey begins to push. F = maF = ? m = 200kg a = 1.52ms-2 F = 200 x 1.52 F = 304N

  11. Newton’s First Law continued… Team Australia came in at 28th out of 30 in this event )after their training efforts on sand slopes in the outback didn’t really pay off...) Heath and Duncan made their way to the bottom of the circuit, and once at the end they continued sliding for 800m along the flat ice. During this 800m slide they were moving at a constant speed. They did not stop until Duncan got out and dug his feet into the ice. Explain why they continued moving using Newton’s First Law and the equation F = ma

  12. Newton’s Laws of Motion Newton’s second law: Acceleration is produced when a force acts on a mass. The greater the mass (of the object being accelerated) the greater the amount of force needed (to accelerate the object).

  13. Newton’s Second Law During the men’s big hill ski jump event KamilStoch of Poland jumped 132.5m taking the gold medal. Kamil has a mass of 55kg. The 29th place holder in the event, IlmirHazetdinov weighed in at 67kg. Using Newton’s second law, explain and justify why Kamil has an advantage over Ilmir.

  14. Newton’s Laws of Motion Newton’s third law For every action there is an equal and opposite re-action.

  15. Newton’s Third Law Russian figure skater won the gold medal with outstanding ability to move around the ice. Julia Lipnitskaia uses the blades of her skates to create a forward motion/ force. Explain and justify what Julia does that creates the forward motion that allows her to glide across the ice.

  16. Tension Tension is the force that exists within or is applied by a rope or wire. The rope experience equal and opposite forces. If something is hanging off a rope and is stationary we can calculate the tension force supporting it based on its mass.

  17. Tension On the way up to the top of the hill on the T-bar tow, 2 of the NZ athletes at the Olympics get stuck wen the tow stops. They are suspended by a wire. Adam has a mass of 82kg, and Shelly of 64kg. Calculate the size of the tension and the weight force in the wire supporting them.

  18. Tension On the way up to the top of the hill on the T-bar tow, 2 of the NZ athletes at the Olympics get stuck wen the tow stops. They are suspended by a wire. Adam has a mass of 82kg, and Shelly of 64kg. Calculate the size of the tension and the weight force in the wire supporting them. F = ma F = (82kg + 64kg) x 10ms-2 F = 146 x 10 F = 1460N Therefore the weight force of the athletes is 1460N, and for the athletes to be supported there, the tension in the wore must also be 1460N

  19. Activities Activity 10A: Using Newton’s laws Page 117-118

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