# Describe qualitatively the relationship between force mass and acceleration

### What is the relationship between force and acceleration? | How Things Fly

F = ma, you already know. But remember that F in this relation is the sum total of all forces acting on the object. In this sense the term "force. Acceleration is caused by a force, eg gravity or friction, acting on a moving object. The relationship between force, mass and acceleration is expressed in the. Consistent with the above equation, a unit of force is equal to a unit of mass Furthermore, the qualitative relationship between mass and acceleration can be .

And similarly, rows 4 and 5 show that a halving of the mass results in a doubling of the acceleration if force is held constant. Acceleration is inversely proportional to mass.

Whatever alteration is made of the net force, the same change will occur with the acceleration. Double, triple or quadruple the net force, and the acceleration will do the same.

On the other hand, whatever alteration is made of the mass, the opposite or inverse change will occur with the acceleration. Double, triple or quadruple the mass, and the acceleration will be one-half, one-third or one-fourth its original value.

The Direction of the Net Force and Acceleration As stated abovethe direction of the net force is in the same direction as the acceleration. Thus, if the direction of the acceleration is known, then the direction of the net force is also known. Consider the two oil drop diagrams below for an acceleration of a car. From the diagram, determine the direction of the net force that is acting upon the car.

Then click the buttons to view the answers. If necessary, review acceleration from the previous unit. See Answer The net force is to the right since the acceleration is to the right. An object which moves to the right and speeds up has a rightward acceleration.

## Forces, mass and acceleration

This represents a time of 0. Her acceleration would be: You can say that her speed decreased by 0. The negative sign tells you that it is a deceleration. Contrast the stopping distances at each speed limit. It is recommended that the distance between your car and the car in front be equivalent to the reaction distance at that speed. You can write this as: If any of these things happen, then a force caused it.

Acts in the opposite direction to the movement or attempted movement. Air resistance and drag: Like friction, it acts in a direction opposite to the movement.

### BBC - GCSE Bitesize: Forces, mass and acceleration

Acts upwards, opposing the weight force. That is, a force is required to get something moving. If an object is moving it will continue to do so in a straight line at a constant speed unless acted upon by a net unbalanced force 34 Crash test dummies have been used for over 30 years to develop safer cars. Before that, live but anaesthetised pigs were used in crash tests. A large pork BBQ often followed. Human corpses cadavers were also used in tests. Accelerometers and force meters were implanted in the cadavers to measure what was occurring.

The results from these experiments led to the development of the modern crash test dummy, the Hybrid 3. Live humans were tested before the invention of the dummies, and Colonel John Stapp underwent 26 tests. Inertia kept his internal body parts and blood moving and he stated later that he felt as if his eyes would fly out of his skull.

Blood vessels in his eyes burst and they bled profusely for 10 minutes after the test. His lungs also collapsed, but he recovered quickly, proving that it was possible to survive such extreme forces.

Something will happen if a force is applied: Calculate the force being applied if: Calculate the acceleration caused by: The brakes of a car can exert a stopping force of N. The car is 1. Rockets expel massive quantities of gases in one direction, which push the rocket in the opposite direction, usually upwards. The exhaust gases are tiny particles but their effect is dramatic due to their high acceleration.

The exhaust is produced when fuel, called propellant, undergoes chemical combustion 43 The resulting exhaust stream produces thrust—the force which propels the rocket. When thrust equals weight the rocket begins to hover, and when thrust is larger than weight, it lifts off 44 45 Flying frozen chickens!

It is estimated that 30 birdstrikes occur worldwide each year, leading to damaged aircraft windscreens and even engine failure. The USA designed a unique device for testing the strength of windscreens on aeroplanes.

The British decided to test a windscreen on a new ultra- fast train. The British were stunned and contacted the FAA to see if everything had been done correctly. The FAA reviewed the test and had only one recommendation: This value is for objects falling in a vacuum. In air, acceleration will be slightly less. An object pushes air out of its way as it falls. The air pushes back with an equal, upward force called air resistance.

Eventually it balances weight, and so the total force acting is zero. There can be no more acceleration and the object falls at a constant speed, called its terminal velocity.

All objects have a terminal velocity, but its value will depend on the shape and size of the object. A sheet of paper has high air resistance and a low terminal velocity, while the same paper crumpled has lower air resistance and will reach higher speeds.

However, skydivers can control their descent by changing the shape of their body as they fall.

It is the force that pulls objects down to the surface of a planet. Weight depends on the mass of the object and the acceleration due to the gravity of the planet itself. When in orbit, the space shuttle and space stations fall towards Earth. Energy is the ability to do work. Work happens whenever things are shifted or rearranged by a force. The bigger the force, the more work done. Likewise if something is shifted a long way, then more work is done than if it only moves slightly.