3 - Motion Flashcards
What is the equation of speed?
v = change in x/change in t.
How are stationary, constant speed and varying speed shown on a distance-time graph?
Horizontal,sloped,wiggly.
Define instantaneous speed.
Speed at a specific instant in time.
How are stationary, constant speed, varying and backwards speed shown on a displacement-time graph?
Horizontal, sloping, curved, negative gradient.
How are stationary, constant inc acceleration, constant dec acceleration and varying velocity shown on a velocity-time graph?
Horizontal, sloping up, sloping down and squiggly line.
What do the letters of suvat stand for?
displacement
initial velocity
final velocity
acceleration
time
What are the 4 suvat equations?
v = u + at
s = ut + 1/2at^2
s = 1/2(u + v)t
v^2 = u^2 +2as
What is stopping distance?
Total distance travelled from seeing a reason to stop and stopping.
What is thinking distance?
Distance from seeing reason to stop and hitting brake.
What is braking distance?
Distance from brake applied to stopping.
What is the equation for stopping distance?
Thinking + braking = stopping.
What are these distances affected by?
.Speed of vehicle.
.Brake/tire/road surface conditions.
.Weather.
.Driver alertness.
.Reaction time/speed.
What is the equation for thinking distance?
Speed x reaction time.
Define gravitational force.
Force exerted by objects with mass energy on objects with mass.
Define free fall.
Object accelerates with no other forces acting upon it.
What is the value of acceleration by freefall downwards?
9.81 ms^-2 (varies due to geology, altitude and latitude).
How do you calculate acceleration due to gravity?
- Drop ball over distance and time.
- Hold ball over trapdoor with electromagnet and timer stopped when electrical contact breaks.
.Time delays.
.Light gate - beams of light broken.
.Stroboscope - strobe light/exposure at time intervals.
.Use s = ut + 1/2at^2.
How does projectile motion work?
.Drop 2 balls - one horizontally and one vertically.
.Both fall at same rate.
.Only changes due to g.
.No air resistance.
.Horizontal v is constant.
.Vertical v changes due to g.
.Use suvat.
.Ha = gcos(90) = 0.
How do you work out trajectory?
sqrt Vv^2 + Vh^2.
tan-1 (Vv/Vh).
How do you deal with firing upwards?
Time of flight - vertical component.
Vv = vsin0.
Vh = vcos0.
