force revision

Question 1

What does the term stopping distance mean?

Answer 1

Definition of stopping distance. : the distance that a driver needs in order to safely bring a vehicle to a complete stop.

Question 2

What does the term thinking distance mean?

Answer 2

thinking distance(Noun) The distance travelled by a vehicle between the time that it needs to brake is perceived and the time that the brakes are applied.

Question 3

What does the term braking distance mean?

Answer 3

Braking distance refers to the distance a vehicle will travel from the point where its brakes are fully applied to when it comes to a complete stop. It is affected by the original speed of the vehicle, the type of brake system in use, the reaction time of the driver/rider and the coefficient of friction between its tires and the road surface.

Question 4

What is the equation that links stopping distance, braking distance and thinking distance

Answer 4

stopping distance = thinking distance + braking distance stopping distance = 6 + 32 stopping distance = 38 m

Question 5

What are the factors that affect the thinking distance?

Answer 5

Factors affecting the thinking distance. Speed is the first obvious factor. The faster you are going, the further you will travel for the same ‘best’ reaction time you can manage, so the greater the thinking distance, which you can do nothing about. The longer your reaction time, the greater your thinking distance.

Question 6

What are the factors that affect the braking distance?

Answer 6

Brakes: The condition of the car’s brakes will affect braking distance, so keep them in good working order. Tyres Different tyres have different wet and dry grip depending on their tread pattern and the rubber used.
Weather conditions If the road is wet or icy, this will significantly increase braking distances.

Question 7

Which distance increases more when you go faster – braking distance or thinking distance?

Answer 7

A faster speed increases both thinking and braking distance, increasing the total stopping distance. You might be asked to look for patterns in car stopping distances, and how they change with the speed of a car. Look at the diagram and answer the question.

Question 8

What is the smallest number of forces that we need to apply to cause an object to deform?

Answer 8

A force is any influence that causes an object to undergo a specific change. Related concepts include:
thrust - increases the velocity of an object,
air resistance - decreases the velocity of an object, torque - changes the rotation of an object.
The Thrust supersonic car (ThrustSSC) was the first car to break the sound barrier when it was driven at 763 miles per hour in 1997. It has huge thrust and is streamlined to minimise air resistance.

Question 9

What does the term ‘elastic deformation’ mean?

Answer 9

Elastic deformation refers to a temporary deformation of a material’s shape that is self-reversing after removing the force or load. Elastic deformation alters the shape of a material upon the application of a force within its elastic limit.

Question 10

What does inelastic (plastic) deformation mean?

Answer 10

Also called plastic deformation. Inelastic deformation occurs when an object is stretched beyond its elastic limit. When the applied force is removed the object may shrink but not return to its original size - it has been stretched.

Question 11

What does the word ‘extension’ mean?

Answer 11

a length of electric cable which permits the use of appliances at some distance from a fixed socket.

Question 12

What is the equation that relates the force and extension of a spring?

Answer 12

The extension of an elastic object, such as a spring, is described by Hooke’s law: force = spring constant × extension [F = k~e]

Question 13

What is the relationship between the spring constant and how hard it is to stretch a material?

Answer 13

When you compress or extend a spring – or any elastic material – you’ll instinctively know what’s going to happen when you release the force you’re applying: The spring or material will return to its original length.

Question 14

What is Hooke’s law?

Answer 14

a law stating that the strain in a solid is proportional to the applied stress within the elastic limit of that solid.

Question 15

What is elastic potential energy?

Answer 15

Elastic potential energy is energy stored as a result of applying a force to deform an elastic object. The energy is stored until the force is removed and the object springs back to its original shape, doing work in the process. The deformation could involve compressing, stretching or twisting the object.

Question 16

What do the letters k and e stand for in the equation for elastic potential energy?

Answer 16

elastic potential energy (Ee) is measured in joules (J) spring constant (k) is measured in newtons per metre (N/m) extension (e), referring to the increase in length, is measured in metres (m) This equation also works for the reduction in length when a spring is compressed.

Question 17

What does the gradient of a force extension graph tell you?

Answer 17

The gradient of a graph is, so if you plot force on the y axis and extension on the x axis, the gradient will give you the spring constant since we have. However, since force is your independent variable, you may want to plot force on the x axis and extension on the y axis, which is probably the case here.

Question 18

What does the area under a force extension graph tell you?

Answer 18

As its a force-extension graph, and work done is then the area under a F-x graph will represent work done. In this case, the upper curve represents the work done on the object against tension while extending it, and the lower curve is the energy recovered (work done by the object) when the object returns to a state of no tension.

Question 19

What is the limit of proportionality of a spring and how do you recognise it on a graph?

Answer 19

Spring constant is a measure of the stiffness of a spring up to its limit of proportionality or elastic limit. The limit of proportionality refers to the point beyond which Hooke’s law is no longer true when stretching a material. The elastic limit of a material is the furthest point it can be stretched or deformed while being able to return to its previous shape. Once a material has gone past its elastic limit, its deformation is said to be inelastic. The higher the spring constant, the stiffer the spring. The spring constant is different for different elastic objects. For a given spring and other elastic objects, the extension is directly proportional to the force applied. For example, if the force is doubled, the extension doubles. This works until the limit of proportionality is exceeded.