3.2 Forces in action Flashcards
Whats a resultant force?
A single force which has the same effect as all the forces acting on a body.
What are the 4 fundamental forces of nature?
.Gravitational force
.Electromagnetic force- force holds atoms and molecules together
.Weak interaction- responsible for the process of radioactive decay and is weak in nature.
.Strong interaction- responsible for holding subatomic particles together in the nucleus.
What does tension do?
Accelerate or change the shape of an object.
What happens to the drag on an object as its acceleration increases?
Its drag would increase.
Whats terminal velocity?
When the drag (upwards) becomes equal to the weight of the falling object (downwards), and so the resulant force is zero- then it continues to fall at a constant velocity. This is called terminal velocity.
What is meant by an object being in equilibrium?
Objects are in equilibrium when all the forces acting on them are balanced - there is zero net or resulant force. In terms of notion, the object is either stationary or is travelling at constant velocity.
How can you measure the terminal velocity of a body falling through a fluid?
You can do this experiment to determine the terminal velocity of a sphere of a known mass through a liquid using a measuring cylinder, elastic bands, washing up liquid and a ball bearing.
- Drop the ball bearing into the liquid starting the timer as you do so. At given time periods use the elastic bands to mark the vertical positions of the ball.
- Once the ball bearing has reached the bottom of the tube, measure the distance between each consecutive elastic bands.
- A magnet can be used to take the ball out so you can repeat the measurement.
- For each time period, measure the distance between consecutive elastic bands, record the time period for each and use this data to calculate the average velocity of the ball.
- Once you have several measurements, calculate the mean distance traveled for each time period and use this data to calculate this velocity, v, of the ball for each time period.
- Plot of graph of v on the y-axis against cumulative time from the release of the ball, t, on the x-axis. Draw a curve though the points. Identify the time at which the ball reached its terminal velocity and use this to determine the ‘best’ value of terminal velocity.
What is a turning moment?
The moment of force (turning moment) is the product of a force and the perpendicular distance of its line of action from the point or axis.
Turning moment (Nm) = magneitude of force (N) x distance from the pivot
What is the principle of moments?
Principle of moments- states that for an object to be in rotational equilibrium, the sum of the clockwise moments must equal the sum of the anticlockwise moments.
What is a torque?
A torque is the effect of a couple which occurs when two equal, anti-parallel forces act to produce a rotation.
What is the center of mass?
The single point where all he objects mass can be assumed to be situated.
What is the center of gravity?
The center of gravity of an object is the single point through which the entire weight of the object can be thought to act.
How to work out the volume of irregular shape object?
Eureka can.
Whats Archimedes’ principle?
Archimedes’ principle states that the upwards buoyant force (upthrust) exerted on an object immerse in a fluid, whether fully or partially submerged, is equal to the weight of the fluid that the object displaces.
Equation for density.
Density= mass/ volume
p=m/v
