forces and motion Flashcards
What is a force?
A push or pull that arises from the interaction between objects
What is gravitational force?
A force of attraction between all objects with mass
How does mass affect gravitational force?
The more massive the object, the greater the gravitational force exerted by it
What is a reaction force?
A push force exerted by a surface on an object resting on it, acting perpendicular to the surface
What does friction do?
Frictional forces always oppose the motion of an object, causing it to slow down
What is drag force?
A type of frictional force that occurs when an object moves through a fluid
What is air resistance?
A specific type of drag force that opposes the motion of an object moving through air
What is thrust?
A force produced by an engine that speeds up the motion of an object
What is upthrust?
An upward-acting push force exerted by a fluid on an object that is submerged in it
What is electrostatic force?
A force between charged objects where like charges repel and opposite charges attract
What is magnetic force?
A force between objects with magnetic poles where like poles repel and opposite poles attract
What is tension?
A force that occurs in an object that is stretched, acting across its length
How can forces affect an object?
Forces can change speed, direction, or shape of an object
What are scalar quantities?
Quantities that have magnitude but not direction
What are vector quantities?
Quantities that have both magnitude and direction
What is the difference between distance and displacement?
Distance is a scalar quantity (magnitude only), while displacement is a vector quantity (magnitude and direction)
What is speed?
A measure of the distance traveled by an object per unit time, regardless of direction
What is velocity?
A measure of the displacement of an object per unit time, including the direction
What is the relationship between mass and weight?
Mass is a scalar quantity, while weight is a vector quantity with both magnitude and direction
What is resultant force?
A single force that describes all of the forces operating on a body
How do you calculate resultant force?
By adding forces in the same direction and subtracting forces in opposite directions
What are balanced forces?
Forces that cancel each other out, resulting in no resultant force
What are unbalanced forces?
Forces that do not cancel out completely, resulting in a resultant force
What does the equation F = m × a represent?
The relationship between resultant force (F), mass (m), and acceleration (a)
True or False: Friction always acts in the direction of motion.
False
Fill in the blank: Frictional forces always act in the ______ direction to the object’s motion.
opposite
What happens when two opposing forces push on each end of a spring?
The spring changes shape (it compresses)
What is a tug-of-war an example of?
Unbalanced forces
What is the resultant force?
The force on an object when forces do not cancel out
What does the resultant force cause an object to do?
Accelerate, speed up, slow down, or change direction
What is the equation relating resultant force, mass, and acceleration?
F = m × a
In the equation F = m × a, what does F represent?
Resultant force, measured in newtons (N)
In the equation F = m × a, what does m represent?
Mass, measured in kilograms (kg)
In the equation F = m × a, what does a represent?
Acceleration, measured in metres per second squared (m/s²)
What is Newton’s second law of motion?
F = m × a
What is the definition of weight?
The force experienced by an object with mass in a gravitational field
How are weight and mass different in physics?
Mass is a scalar quantity; weight is a vector quantity
What is the equation relating weight, mass, and gravitational field strength?
W = m × g
What is the gravitational field strength on Earth?
10 N/kg
What does ‘g’ represent in the weight equation?
Gravitational field strength, measured in N/kg
What is the relationship between mass and weight?
They are directly proportional
What is the stopping distance of a car?
Total distance travelled during the time it takes to stop in an emergency
What is stopping distance calculated from?
Thinking distance + Braking distance
What factors affect thinking distance?
- Speed of the car
- Reaction time of the driver
What is the average human reaction time?
0.25 seconds
What increases reaction time?
- Tiredness
- Distractions
- Intoxication
What is braking distance?
Distance travelled under the braking force
How does speed affect stopping distance?
Greater speed results in a larger stopping distance
What is terminal velocity?
The fastest speed an object can reach when falling
What forces act on falling objects?
- Weight
- Air resistance
What happens when an object reaches terminal velocity?
Upward and downward forces are balanced, resultant force is zero
What is the relationship between air resistance and speed?
Air resistance increases as speed increases
What is the force of gravity on an object called?
Weight
What is the aim of the experiment investigating force and extension?
To investigate the relationship between force and extension for a spring and a rubber band
What is the independent variable in the force and extension experiment?
Force, F
What is the dependent variable in the force and extension experiment?
Extension, e
What equipment is used to measure extension?
Ruler
What is the resolution of the measuring equipment used?
1 mm
What is the purpose of a ruler in the experiment?
To measure original length and extension
What is the role of the 100 g mass hanger?
To hold additional masses
What does the pointer (fiducial marker) help with?
To accurately read the extension from the ruler
What is the resolution of the measuring equipment used?
Ruler = 1 mm
What is the independent variable in the experiment investigating force and extension for a metal wire?
Force, F
What is the dependent variable in the same experiment?
Extension, e
What is the formula for weight, W?
W = m × g
What does ‘g’ represent in the equation W = m × g?
Gravitational field strength on Earth in N/kg
How is the extension e calculated for a spring/rubber band?
e = average length – original length
How is the extension e calculated for a metal wire?
e = new marker reading − reference point reading
What does Hooke’s Law state?
The extension of an elastic object is directly proportional to the force applied, up to the limit of proportionality
What happens to the relationship between force and extension beyond the limit of proportionality?
It is no longer directly proportional
What is elastic behaviour?
The ability of a material to recover its original shape after the forces causing the deformation are removed
Define elastic deformation.
When the object returns to its original shape after the deforming forces are removed
Give examples of materials that undergo elastic deformation.
- Rubber bands
- Fabrics
- Steel springs
Define inelastic deformation.
When the object does not return to its original shape after the deforming forces are removed
Give examples of materials that undergo inelastic deformation.
- Plastic
- Clay
- Glass
What is the purpose of using a G-clamp in the experiments?
To secure the clamp stand to the bench so that the equipment does not fall over
What should be done to avoid parallax error when taking measurements?
Make sure the measurements on the ruler are taken at eye level
What safety measure should be taken while conducting the experiment?
Wear goggles during this experiment in case the spring, rubber band, or wire snaps
What is a common mistake when measuring extension?
Calculating the increase in length by each time instead of the total extension
What is the significance of the limit of proportionality?
It is the point beyond which the relationship between force and extension is no longer directly proportional
Fill in the blank: The extension measures how much the object has stretched by and can be found by subtracting the _______.
original length from each of the subsequent lengths
terminal velocity
object is accelerating
MP2. downward force greater than upward force
MP3. gradient / acceleration decreasing
MP4. drag increases as speed increases;
MP5. resultant force decreases;
MP6. idea that downward force=
upward force;
MP7. idea that acceleration is
zero
MP8. terminal velocity achieved
proof of hookes law
MP1. quotation of Hooke’s Law; i.e. force and extension
should be proportional
MP2. line is straight
MP3. line passes through origin;
MP4. no evidence of having passed elastic limit;
hookes law practical 5 marks
MP1. measure original length of spring;
MP2. measure new length / extension for a range
of masses;
MP3. extension = new length – original length;
MP4. use of ruler; allow tape measure
MP5. method of avoiding parallax, e.g. look at eye
level or use a pointer;
MP6. use of a set square / clamping ruler
vertically;
MP7. idea of measuring between the same two
points (on the spring);
MP8. idea of repeating and averaging; allow repeating to identify
anomalies
MP9. idea of measuring extension with decreasing
mass as well;
