Forces Flashcards
What unit are forces meausred in?
Newtons
What are forces?
Forces are pushes or pulls that make something start or stop moving
State 7 different things that forces can do
Start something moving
Stop something moving
Twist things
Make things turn
Compress things
Stretch things
Balance each other out
What do we call forces that have the same strength but point in opposite directions
Balanced forces
What do we call two forces that act in different directions and have differnt sizes
Unbalanced
In which direction does this ball speed up?
Explain why this happens
The ball will accelerate (speed up) to the right
This is because the forces are unbalanced. The ball moves to the right because the largest force is pointing to the right
Explain why the Newton meter does not move in this picture
The newton meter does not move because the forces acting on it are balanced.
Why does this bus (The Mystery Machine) move at a steady speed
The forces on The Mystery Machine are balanced. This means it does not speed up or slow down, so it must be moving at a constant speed.
Which force slows things down when two surfaces rub together?
Friction
Which force stops you from falling through the floor?
The normal reaction force
Which force makes a boat float
Upthrust
Which force pulls you towards the earth?
Weight
Which force is caused by the pull of a stretched elastice band?
Tension
Which force holds up a tower from the bottom?
Compression
Which force acts on metals only and is caused by North and South poles
Magnetic force
Which force slows down a falling skydiver
Air resistance (drag)
What is the name of the force that speeds things up?
Thrust
What causes the force of friction?
Friction is caused by rough surfaces rubbing against each other
The rougher the surfaces are, the larger the force of friction
How can we reduce friction?
Lubricants, such as oil, reduce friction by filling in the gaps and stopping the rough surfaces from rubbing against each other.
Explain what streamlining is
Stremlining is when the shape of an object helps to reduce air resistance, this is done by making the object longer or more pointy
Explain when friction is useful or when friction is not useful
Friction is useful when we do not want things to slide, for example friction between your feet and the floor helps you to walk
Friction is not useful when you want to slide, for example friction between ice skates and the ice would slow you down so it is not helpful
What is the difference between mass and weight?
Mass is the ammount of stuff there is
Weight is the force of gravity on an object
Explain what this formula tells us
W = m x g
This force tells us that to find the force of weight we need to multiply together the mass of the object and the strength of gravity of that planet
W = Weight (N - Newtons)
m = mass (kg - kilograms)
g = strength of gravity (m/s2 - meters per second squared)
What is the relationship between the size of a planet and the strength of gravity?
How does this affect the weight?
The larger the planet the stronger the strength of gravity
If someone goes to another planet, their mass stays the same but the weight increases becuase the strength of gravity increases.
What happens to the tension force of a spring when the string is stretched?
When the spring is stretched the force of tension increases.
What is the resultant force in this picture.?
Explain how you work out a resultant force
The resultant force is 20N to the right.
You work out a resultant force by subtracting the smaller force from the bigger force. The direction is always the direction of the bigger force.
