# Newton's Laws and Momentum

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- Created by: Agata
- Created on: 24-02-16 16:03

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- Newton's Laws and Momentum
- Momentum
- LINEAR MOMENTUM: The mass of an object multiplied by its velocity. It is a VECTOR. (symbol: p , units kg*m/s).
- p = mv
- The reason for using the term linear momentum is that there is another term, angular momentum for objects rotating.

- Momentum = force x distance= change in momentum Ft=mv-mu Unit: Ns VECTOR

- LINEAR MOMENTUM: The mass of an object multiplied by its velocity. It is a VECTOR. (symbol: p , units kg*m/s).
- WORKED EXAMPLE A truck going north along a motorway has a mass of 4000 kg and a velocity of 18 m/s. A car also going north along the motorway, has a mass of 1400 kg and a velocity of 35 m/s .
- A) Calculate the kinetic energy of each vehicle. ANSWER: Truck : 1/2 x 4000 x 18 ^2 = 648 000 J. Car: 1/2 x 1400 x 35^2 = 857500.
- kinetic energy = 1/2 m v ^"

- C) Calculate the distance each vehicle takes to stop against retarding force of 7000N ANSWER Truck: 18^2/( 2 x 1.75 ) = 92.6m Car: 35^2 /(2 x 5.0) = 122.5m
- s=v^2/2a

- A) Calculate the kinetic energy of each vehicle. ANSWER: Truck : 1/2 x 4000 x 18 ^2 = 648 000 J. Car: 1/2 x 1400 x 35^2 = 857500.
- Kinetic Energy K.E= force x distance = change in K.E Fd=1/2mv^2- 1/2mu^2 Unit: Nm = J SCALAR

- Momentum
- B) Calculate the momentum of each vehicle. ANSWER Truck: 4000 x 18 = 72 000 due north Car: 1400 x 35 = 49 000 due north.
- p=mv
- WORKED EXAMPLE A truck going north along a motorway has a mass of 4000 kg and a velocity of 18 m/s. A car also going north along the motorway, has a mass of 1400 kg and a velocity of 35 m/s .
- A) Calculate the kinetic energy of each vehicle. ANSWER: Truck : 1/2 x 4000 x 18 ^2 = 648 000 J. Car: 1/2 x 1400 x 35^2 = 857500.
- kinetic energy = 1/2 m v ^"

- C) Calculate the distance each vehicle takes to stop against retarding force of 7000N ANSWER Truck: 18^2/( 2 x 1.75 ) = 92.6m Car: 35^2 /(2 x 5.0) = 122.5m
- s=v^2/2a

- A) Calculate the kinetic energy of each vehicle. ANSWER: Truck : 1/2 x 4000 x 18 ^2 = 648 000 J. Car: 1/2 x 1400 x 35^2 = 857500.

- D) Calculate the time each vehicle takes to stop against a retarding force of 7000N. ANSWER Truck: 18/1.75=10.3s Car: 35/5=7.0s
- t=v/a

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