Download
1 / 32
320 likes | 522 Views
Chapter 4 Linear motion. 1) You can describe the motion of an object by its position, speed, direction and acceleration. 2) Distance is a scalar. Distance is “how much ground is covered” during motion. .
E N D
1) You can describe the motion of an object by its position, speed, direction and acceleration
2) Distance is a scalar. Distance is “how much ground is covered” during motion.
3) Displacement is a vector Displacement is DX “final position – initial position”
4) Motion is relative.An object is moving if its position relative to a fixed point is changing.
5)Example: A crate on a train traveling at 20 m/sec. The crate is at rest wrt the train.But the crate is moving 20 m/sec relative to the ground.
6) Unless stated otherwise, we measure speed relative to the Earth.
7) Speed is how fast an object is moving. Speed is a scalar quantity.
8) From motion experiments, Galileo defined Speed = distance/timeBefore Galileo, motion was simply described as “fast” or “slow”
9) Instantaneous speed is the speed at any instant.10) A speedometer shows instantaneous speed.
12) Velocity = speed in a given direction. Velocity is a vector quantity.
13) Constant velocity = means same speedin same straight-line direction.
14) Changing velocity : if either the speed changes or the direction changesor both change
15) Acceleration is the rate of change of velocityacceleration is a vector.16) acceleration = change of velocity time interval
18)Acceleration is due to change in direction of moving object
19) Accelaration for object in a straight line = change in speedtime interval
20) projectile: an object that moves only under the influence of gravity.21) Free fall = object falling under influence of gravity.
22) When we talk about free fall, we ignore air resistance.
23) Acceleration of object in free fall is about g= 10 meters/sec2
24) 6 kinematic variables in y and xy xyoxo vyvxvoyVoxay axt t
25)For object moving only in y direction, Y = final position in y directionYo = initial position in y directionVoy = initial velocity in y directionVfy = final velocity in y directionay = -gt = time elapsed
26) What is meant by “-g”?The object is accelerating in the negative direction
27) For object moving only in x direction x = final position in x directionxo= initial position in x directionVox= initial velocity in x directionVfx= final velocity in x directionay = acceleration in x directiont = time elapsed
27) Kinematic Equations y = yo + vot + ½ a t2V = vo + atx = xo + vot + ½ a t2V = vo + at
28) For An object dropped from height h in free fall, equations simplify y = h - ½ g t2V = -gt
26) Rising objects: an object thrown straight up will slow down, stop and fall back down
