UNIT1 - dynamics Flashcards
What is the difference between a scalar and a vector?
SCALAR is a physical quantity with ONLY MAGNITUDE.
VECTOR is a physical quantity with MAGNITUDE AND DIRECTION.
What are some scalar quantities?
Speed Temperature Energy Mass Distance Time
What are some vector quantities?
Displacement
Velocity
Acceleration
Force
What is speed and what are it’s units?
Speed is how fast a body is travelling.
Metres per second.
What is energy, what forms can it be in and what are it’s units?
The capacity for doing work.
Kinetic, potential, thermal, electrical, chemical or nuclear.
Joules
What is the difference between distance and displacement?
Distance is how far a body has travelled.
Displacement is how far a body has traveled in a direction from its origin.
What is velocity?
A measure of a body’s speed and direction.
What is acceleration and what are it’s units?
Acceleration is the speed gained by a body every second OR rate of change of velocity of a body with respect to time.
Metres per second per second.
What is a force and what are it’s units?
An interaction with a body that causes a change in the motion of the body.
Newtons.
A car travels 20km East and then 30km West.
What is the cars displacement?
Draw vector diagram TO SCALE.
State displacement.
Answer: 10km West
A car travels 50km West and 70km South.
What is the cars displacement?
METHOD 1 - use pythagoras
METHOD 2 - draw diagram TO SCALE, using ruler measure resultant vector and then use protractor from North to get degrees for direction.
Answer: 86.02km (plus degrees)
What are the 3 formulas concerning
- speed/velocity (v)
- distance (d)
- displacement (s)
- time (t)
S=v x t
S=average v x t
D= average v x t
Describe an experiment to measure average speed.
A small vehicle is placed on a slope, we measure slope and measure from back of vehicle its total distance travelled.
We time how long it takes to go down the slope.
Repeat 3 times.
Using average time calculate speed by dividing distance by time.
Describe an experiment to measure instantaneous speed.
A small vehicle with a small bit of card attached at the top is placed on a slope. A light gate is connected to a QED meter as a timer. This times the vehicle as it goes through the light gate.
We then divide the length of the card by the time measured by the light gate.
How do we calculate acceleration?
A=(v-u)/t
(Final speed-initial speed) ÷ time
Describe an experiment to measure acceleration.
A small vehicle with a small bit of card attached to the top is placed on a slope. As it travels it passes through 2 light gates connected to a timer giving us our 2 values for speed. We also measure time between gates.
What is Newtons first law?
A body at rest or moving in a straight line with a constant velocity will continue to be at rest or continue to move in a straight line unless acted on by an unbalanced force.
What is Newtons second law
The acceleration of a body is directly proportional to the unbalanced force acting on the body. (straight line from origin increasing)
F1/F2=A1/A2
The acceleration of a body is inversely proportional to its mass. (line from high on y axis curving down)
A1/A2=M2/M1
What is Newtons third law?
For every action force there is an opposite and equal reaction force.
What are the 2 equations involved in forces?
Force=mass÷acceleration
Weight=mass x gravitational field strenth
What is the difference between weight and mass?
Weight is a force, mass is not.
