Forces up to level 6 Flashcards
Explain the difference between a scalar and a vector
Scalars have size (magnitude) only
Vectors have both magnitude and direction
What are the three main vectors that you need to know at GCSE level?
Force (pushes and pulls)
Velocity (speed with direction)
Displacment (distance with displacement)
Which of these quantities are scalar and which are vectors:
time
mass
velocity
speed
displacment
distance
force
acceleration
volume
pressure
area
time = scalar
mass = scalar
velocity = vector
speed = scalar
displacment = vector
distance = scalar
force = vector
acceleration = vector
volume = scalar
pressure = scalar
Explain how forces are represented on a diagram
Example: sketch a diagram of the weight force acting on a falling ball
Forces are represented as arrows. The arrow starts on the object that the force is acting on an points in the direction the force is acting.
The length of the arrow represents the size of the force.
Example:
Explain the difference between contact and non-contact forces and give examples of each one
A contact for is a force that requires the two bodies to be touching for the force to act.
Examples: friction, air resistance, normal reaction force
A non-contact force is a force where the two bodies do not need to be touching for the force to act.
Examples: Weight, magnetic force, electric force
What is the unit of force?
What is its symbol?
The Newton
N
Explain how to use a scale diagram to represent the magnitude of forces
the length of a force arrow represents the size of the force. Create a scale where 1 cm is equivalent to a set number of Newtons. All the forces on that diagram must follow the same scale.
How do pairs of forces act when they are:
a) acting along the same line
b) offset from each other
a) if forces are acting along the same line they will add to create a resultant force. if the forces act in the same direction their magnitudes are addes, while they are subtacted if the forces are acting in opposite directions
b) if the forces are not acting along the same line then the object will begin to spin around. if the forces are acting in the same direction the object will move and spin.
Explain how you would investigate how different types of lubricant affect the size of the force of friction when one object slides over another.
- set up the equipment as shown in the diagram
- pull the block at a constant speed and measure the force required to do this. This is equal to the friction force between the block and the surface
- Repeat this 3 times and take an average
- add a lubricant to the surface of the block and repeat the investigation. Again do this 3 times and take an average
- Find the difference between the force required with and without the lubricant to assess the size of its effect
- Repeat the experiment with a range of different lubricants
Label the forces that are acting on this object
What is the resultant force of these two objects?
50N Upwards
What is the resultant force on this object?
5N Down
What is the effect on a stationary object of:
a) a resultant force of zero
b) a resultant force greater than zero
a) The object will remain at rest
b) The object will accelerate in the direction of the force
What is the effect on a moving object of
a) a resultant force of zero
b) a resultant force in the direction of motion
c) a resultant force opposite to the direction of motion
a) The object will continue to move in a straight line at a constant speed
b) the object will accelerate in the direction of the force
c) the object will decelerate (slow down)
Explain how to find the centre of mass of a symmetrical piece of card
Draw lines down two of the lines of symmetry, the centre of mass will be where the lines cross.