#### Transcript Slide 1

Horizontally III. _______________________Fired Projectile: A projectile (object) is launched horizontally initial speed vi. from a height ______ with an __________________ . h air resistance Assume no_____________________. vi h The time in the air before landing is called the ____________________. time of flight the range horizontal distance traveled = _____________ dropped Ex. Ball 1 is________________. horizontally Ball 2 is fired __________________ 1 2 vi at the same time Both reach the ground ______________________ , initial speed mass regardless of 2's __________________ or ________. independent of the x motion. The y motion is ______________ Remember: horizontally fired projectile The time it takes a ______________ equal to to fall is ______________ the time it takes a dropped ______________ ball to fall from the same height. air resistance With no ____________________, only the force of gravity acts on the object: ___________ vi gravity The trajectory (path) parabola is a________________. opposite Air resistance acts in the direction _____________ decreases to its velocity. This ___________________ its range. vi air resistance gravity no The trajectory is _____ longer ___________ a parabola. 1.Since the object moves in 2 dimensions, each d, v and a must be replaced by their components: dx, vx, ax For x motion: d, v, a _______________ dy, vy, ay For y motion: d, v, a _______________ gravity , 2. No air resistance only ____________ downward -y direction. which is _______________ , in the ____ horizontal or x force. Because There is no _________________ of this, the only acceleration a is purely vertical: -9.81 m/s2 ay = ___________ 0 ax =____________ horizontal 3. The initial velocity is purely _________________: component viy = ___________ (initially, no y _______________) 0 vix vi = ________ ("horizontally fired") Horizontal (x) motion: ax =______ 0 displacement: d = v t + ½ at2 i dx = vixt + ½axt2 =0 d =v t x dx ix dx = velocity: vf = vi +at vfx = vix + axt =0 vfx = vix t vfx vfx = uniform The x motion is _________________. t Vertical (y) motion: 2 0 -9.8 m/s viy = ____ & ay = __________ displace2 d = v t + ½ at i ment: dy = viyt + ½ayt2 dy = =0 ½(-9.8)t2 |dy| dy = -4.9t2 velocity: vf = vi +at vfy = viy + ayt vfy = 0 + (-9.8)t vfy = - 9.8t t |vfy| t dropped ball The y motion is same as for a _________________. Horizontal (x) motion: Vertical (y) motion: uniform motion •____________ accelerated •______________motion constant x-speed •____________ • same as for a ball dropped from rest ____________________ dx = vixt dy = -4.9t2 vfx = vix vfy = - 9.8t ax = 0 ay = -9.8 m/s2 Ex. A 68-kg clown is fired from horizontal cannon with an initial speed of 40. m/s from a height of 25 m. What is her time of flight? 40. m/s 25 m Given: m= vix = viy = ay = ax = dy = Unknown: t 68 kg 40. m/s 0 -9.81 m/s2 0 -25 m Equation: dy = -4.9t2 -25 = -4.9t2 5.1 = t2 2.3 s = t What is her range? dx = vixt dx = (40.)(2.3) dx = 82 m What is x-component of her velocity after 1.5 s? 40. m/s What is her acceleration after 1.5 s? -9.8 m/s2 down Recalculate the new time of flight and range if 80. m/s. she is fired with an initial speed of ____________ Time of flight: same range: dx = vixt dx = (80.)(2.3) dx = 180 m Ex. A dart fired horizontally strikes a target a distance of 0.15 m below where it is aimed. 0.15 m blow gun What was its time of flight? viy = 0 ay = -9.81 m/s2 Given: ax = 0 dy = -.15 m Equation: dy = -4.9t2 -.15 = -4.9t2 0.17 s = t Unknown: t If the target was 9.0 m away from the gun, what was its initial speed? dx = vixt 9.0 = vix (0.17) vix = 53 m/s horizontal motion -___________ uniform dropped ball vertical motion – ______________ combined motion -________________ parabola vi 1s 2s 3s 4s 1s 2s 3s a= -9.8 m/s2 4s Look at how the velocity changes: vi 1s 2s 3s 4s 1s 2s 3s 4s constant The x-component of v is ________________ decreases The y-component of v __________________ Resultant velocity magnitude (speed) ______________ increases tangent ___________________to trajectory What if it was fired with half of the original vi? vi 1 s 2 s 3s 4s 1s 2s 3s 4s Both fall at the same rate, which equals the rate at which a dropped ball falls. Which ball has the greatest acceleration? Open your 3-ring binder to the Worksheet Table of Contents. Record the title of the worksheet: Horizontally Fired WS