Kinematics

Question 1

avg velocity = ?

Answer 1

displacement/time

Question 2

avg speed = ?

Answer 2

total distance traveled/time

Question 3

are instananeous speed and instantaneous velocity equal?

Answer 3

yes. instan. speed is the magnitude of inst. vel

∆x/∆t

Question 4

are velocity and speed scalar or vector?

Answer 4

speed=scalar

velocity=vector

Question 5

avg accel = ?

Answer 5

∆ inst. velocity/∆t

Question 6

inst accel = ?

Answer 6

dv/dt

Question 7

What does the slope represent on a graph of velocity v. time? What does it mean if this slope is positive or negative?

Answer 7

• inst accel.
• positive slope means positive accel means in direction of velocity
• negative slope means negative accel means in opp direction of velocity means decelaration

Question 8

VAT

Answer 8

v_f-v_i=at

Question 9

What equation would you use when asked for total time of flight for obj w/ non-zero v_i (when object comes back down to original height)?

Answer 9

VAT

v_f-v_i= at

2v_i,y=gt

• time of flight depends only on v_i,y

Question 10

VAX

Answer 10

v_f²-v_i²=2ax

Question 11

What equation would you use when asked for the max height of a projectile?

Answer 11

VAX: v_f²-v_i²​=2ax

v_i,y²=2gh_f

Question 12

what equation would you use when asked for v_f of an object dropped from “h”?

Answer 12

VAX: v_f²-v_i²​=2ax

v_f=√2gh_i

Question 13

TAX

Answer 13

x=v_it + ½ at²

Question 14

what equation would you use for the time of flight for an obj in free-fall?

Answer 14

TAX: x=v_it + ½ at²

h=½ gt² therefore t= √(2h)/g

Question 15

DVT

Answer 15

d=vt

when v is avg velocity: d= ((v_i+v_f)/2) t

Question 16

What equation would you use when asked for horizontal distance traveled by a projectile?

Answer 16

DVT: d=v_xt

• horizontal distance depends only on v_x but get the t, time of flight, from v_y (why 45˚ gives your furthest possible distance traveled)

Question 17

When does an obj reach terminal velocity?

Answer 17

when F_g=F_air

at this point obj stays at v_t (∆v=0) until acted on by another force

Question 18

What happens to v_x and v_y during flight?

Answer 18

v_x stays constant

v_y changes with g

Question 19

terminal velocity = ?

Answer 19

• therefore higher mass–> higher v_t
• k= constant depends on density of air
• v_terminal means accel=0