Unit 2.1 - Distance, Speed and Acceleration

Question 1

What is the distinction between speed and velocity?

Answer 1

Speed is scalar (only has magnitude - it is how fast an object moves); velocity is vector (has direction and magnitude - it is how fast an object moves in a given direction).

Question 2

How can the distance traveled be calculated from a velocity-time graph?

Answer 2

The area under the line represents the distance traveled.

Question 3

Describe how the principles of forces and motion affect safe stopping of vehicles.

Answer 3

Danger when stopping a vehicle is due to the resultant force on the occupants, and resultant force = change in velocity/time, so the greater the speed of the vehicle, the more dangerous a crash would be.

Question 4

What factors affect thinking distance?

Answer 4

Reaction time of the driver (which can be affected by tiredness and alcohol), distractions (e.g. mobile phones) and speed of the car.

Question 5

What factors affect braking distance?

Answer 5

Worn brakes, wet/icy road, mass of the car, worn tires, and speed of the car.

Question 6

Name three safety features of cars and describe in terms of forces how these keep occupants safe.

Answer 6

Air bags, crumple zones and safety/seat belts - these all increase the time for the change in velocity, reducing resultant force.

Question 7

What can be introduced in local areas to keep people safe from collisions?

Answer 7

Speed limits and speed bumps - decrease speed of cars, so shorter stopping distance and less chance of collision; also less kinetic energy, so collisions are less dangerous.