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# Forces

### GCSE Physics and combined science

Question | Answer |
---|---|

A value with magnitude only is a ________? | scalar |

A value with magnitude and direction is a ____________? | vector |

Distance an speed are examples of _________ quantities | scalar |

Force, displacement and velocity are examples of __________ quantities | vector |

What is a contact force? | A force between two object which are touching |

What ia a non-contact force? | A force between objects which are separated by space. |

Give two examples of contact forces | e.g. friction, air resistance |

List three non-contact forces | gravitational, electrostatic, magnetic |

Define weight | The force ofgravity acting on an object's mass |

What device is used to measure weight? | A newtonmeter |

What is the name of the single point at which an object's mass appears to act? | centre of mass |

The center of mas of an object is… | the single point at which the objects weight appears to act. |

The single force which has the same effect as the combination of all the different forces acting on an object is the ______________ _______________. | resultant force |

Work is done when an object is …. | … moved through a distance |

Moving objects with mass are said to have __________? | momentum |

State the law of conservation of momentum | In a closed system the total momentum before an event is equal to the total momentum after an event. |

State the equation which links gravitaional field strength, mass and weight | W=mg |

State the equation which links distance, force and work done | W=Fs |

State the equation which links extension, force and spring constant | F=ke |

State the equation which links distance, speed and time | s=vt |

State the equation which links acceleration, change in velocity and time taken | a=Δv/t |

State the equation which links acceleration, mass and resultant force | F = ma |

State the equation which links mass, momentum and velocity | ρ = mv |

What is the unit of weight? | Newtons (N) |

What is the unit of mass? | kilograms (kg) |

What is unit of gravitational field strength? | newtons per kilogram (N/kg) |

What is the unit of work done? | Joules (J) |

What is the unit of force? | Newtons (N) |

What is the unit of distance? | meters (m) |

What is the unit of the spring constant? | Newtons per meter (N/m) |

What is the unit of the spring extension? | Metres (m) |

What is the unit of speed or velocity? | metres per secons (m/s) |

What are the units of acceleration? | metres per second squared (m/s2) |

What are the units of momentum? | kilogram metres per second (kg m/s) |

When a spring is stretched and can then return to its original length it is known as __________ _______________ | elastic deformation or elastic behaviour |

When a spring is stretched and its length is permanently altered it is known as ___________ ____________ | Inelastic deformation or inelastic behaviour |

The limit of proportionallity of a spring is… | the length a spring can be stretched to before it no longer returns to its original length |

Sketch the Force (y) -Extension (x) curve for stretching a spring from no force to beyond its elastic limit. | teacher to draw on board… |

The stopping distance of a vehicle is the sum of the ….. | thinking and breaking distances |

The distance a vehicle travels while the driver is reacting is the … | thinking distance |

The distance a vehicle travels which the driver is breaking is the … | breaking distance |

Reaction time is… | the time it takes a driver to react |

A typical reaction time is … | 0.2-0.9 s |

Factors which influence reaction time are… | tiredness, drug, alcohol, distractions |

Fctors which affect breaking distance are … | weather conditions, conditions of breaks and tyres |

Both thinking and breaking distance are affected by which factor? | speed of vehicle |

The greater the speed of a vehicle, the _________ the force required to stop the vehicle | greater |

The distance and object moves and the direction in which it moves is known as the _________ | displacement |

The speed of an object in a particular derection is its ___________ | velocity |

The change of an objects speed in a given time is the _________ | acceleration |

Acceleration of falling objects close to the earth is ________ | 9.8 m/s2 |

When the force moving an object is balanced by frictional forces it is moving at its _____________ _____________ | terminal velocity |

On a distance time graph a straight line represents… | constant speed |

On a distance time graph a upward curve represents… | acceleration |

On a distance time graph a curved line becoming horizontal represents… | decelleration |

On a distance time graph a horizontal line represents… | stationary |

On a distance time graph the gradient is used to calculate the … | speed or velocity |

On a velocity time graph an upwards straight line represents … | acceleration |

On a velocity time graph a downwards straight line represents … | decelleration |

On a velocity time graph a horizontal line represents … | constant speed |

On a velocity time graph a horizontal line along the x-axis represents… | stationary object |

On a velocity time graph, when the line falls below the x-axis it indicates that the object is … | moving backwards |

Calcuating the gradient of a velocity time graph gives the … | acceleration |

Calculating the area under a velocity time graph gives the … | distance travelled |

A typical walking speed is … | 1.5 m/s |

A typical running speed is … | 3 m/s |

A typical cycling speed is … | 6 m/s |

Sound in air travels at … | 330 m/s |

State Newton's First Law | The velocity of an object will only change if a resultant force is acting on the object. |

If balanced forces act on a moving object it will … | continue to travel at a constant speed |

If balanced forces act on a stationary object it will … | remain stationary |

State Newton's Second Law | Force = mass x acceleration (The acceleration of an object is proportional to the resultant force acting on the object, and inversley proportional to the mass of the object) |

State Newton's Third Law | Whenever two objects interact, the forces they exert on each other are equal and opposite |

The tendency of objects to continue in their state of rest or of uniform motion is known as … | inertia |