Review Exam on Friday REVIEW You are allowed on flash card I will NOT provide formulas What is the resultant of a pair of forces 100N upward and 75N downwards 25N up Why is speed scalar and velocity vector ID: 142314
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Slide1
Wednesday – November 7
Review
Exam on FridaySlide2
REVIEWYou are allowed on flash card.
I will NOT provide formulas.Slide3
What is the resultant of a pair of forces 100N upward and 75N downwards?
25N upSlide4
Why is speed scalar and velocity vector?
Speed is only a number.
Velocity is speed in a given direction.Slide5
What is the end point for:45° for 3 blocks, S for 7Slide6
Calculate the resultant for the following:
8m east, 2m north, 6 m west
2
2
+
2
2
= √8 = 2.9m NESlide7
A ball is dropped from a 60m high building. How far will it have fallen after 3.0 seconds?
y
= ½ gt
2
4.8m/s
2
x 9s
2 = 44.1mSlide8
In the absence of air resistance, why does the horizontal component of velocity for a projectile remain constant?
No other forces are involved.Slide9
Why does motion in the vertical component change?
GravitySlide10
A bird flies at 20km/h. How long does it take to fly 400km?
400km/ 20km/
hr
= 20hoursSlide11
A rock is thrown at a target 40m away. It hits the target in 4.0 seconds. What is the speed of the rock?
40m/4.0 seconds = 10m/sSlide12
A stone is dropped from a bridge and hits the ground after 4.0 seconds. How high is the cliff?
y
= ½ gt
2
4.8m/s
2
x 4.0s
2 = 78.4mSlide13
A salmon jumps up a waterfall to return home to spawn. The waterfall is 2.0m high. What minimum speed must the fish meet to jump the waterfall?
v
f
2
= v
yo
2
+ 2a ∙ d= 6.26m/sSlide14
What is the resultant path of a ship traveling north at 8m/s if the tide is pushing at 2m/s east. What is the angle?
8
2
m/s + 2
2
m/s =
√
68m2/s2= 8.2m/s8/2 tan-1 = 76° Slide15
A rock is dropped and hits bottom 5 seconds later. What is its velocity just before it hits bottom.v
y
=
v
yo
+
a
yt9.8m/s2 x 5 s = 49m/sWhat is the height of the cliff?y = ½ gt
2
= 4.9m/s
2
x 25 s2 = 122.5mSlide16
A rock is thrown from a cliff at 20m/s. What is the horizontal velocity after 2.0 seconds?20m/s
What is its vertical velocity in 2.0s?
y
=
a
y
t
9.8m/s2 x 2.0 s = 19.8m/sSlide17
A rock is thrown from a cliff at 20m/s. What is its horizontal displacement after 3.0s?
x
=
v
xi
t = 20m/s x 3.0s = 60mSlide18
A man shoots a gun at 2m above ground. The bullet is fired and hits the ground 1000m away. What vertical velocity did the bullet hit the ground?v
fy
2
= v
oy
2
+ 2a x d
2(9.8m/s2) x 2m = vfy2√39.2m2/s2 = 6.26m/sSlide19
A ball is projected horizontally from a point 245m above the ground. How long does it take to reach the ground?y
= ½ gt
2
t
2
= y ÷ ½ g
245m ÷ 4.9m/s
2 = √50s2= 7.07 secondsSlide20
A ball is projected horizontally from a point 245m above the ground. How long does it take to reach the ground? = 7 seconds
If the ball strikes 49m horizontally from the point of projection, what is the horizontal velocity?
v
= d/t 49m/7s = 7m/sSlide21
A projectile is shot upward at a 60° angle from the ground at 60m/s. What is the vertical component of velocity?y = 60m/s (sin 60°) = 52m/s
What is its horizontal component of velocity?
v
x
= v (
cos
Ө)vx = 60m/s (cos 60°) = 30m/sHow far in the x direction has it gone in 3 seconds?
x =
vt
30m/s x 3 seconds = 90m