Rank the Vertical Velocity from Largest to smallest

Rank the horizontal displacement from least to greatest.

Explain.

The football has 2 velocities.
Which velocity is the football player matching.

[ Flash ]

Horizontal velocity.
The football and the football player
have a constant horizontal velocity.

St. Mary's Show Me The Physics

 Ex) A projectile leaves ground at an angle of 60.° and a speed of 100.m/s. (a) Find the initial vertical component of the object's velocity

Ex) A projectile leaves ground at an angle of 60.° and a speed of  100. m/s.

(a) Find the initial vertical component of the object's velocity

Ө = 60.°

Vi  = 100. m/s
Viy = ?

Viy = Vi(sinӨ)

= (100. m/s)sin60.°

Viy = 87. m/s up

(b) Find the objects maximum height.

Viy = 87. m/s
ay = -10 m/s2 (ascending)
dy (max) =?
Vfy = 0 (at max height)

02 = (87. m/s)2 + 2(-9.8 m/s2)d

0 = 7569 + -19.6.dy

subtract 7569 from both sides

-7569 = -19.g(dy)

dy = 386 m

Actually ......

dy = 390 m

(2 sig. figs)

 ex) A rock is thrown from a cliff with initial speed of 40. m/s at an angle of 45.° below  the horizontal.  (a) What is the vertical component of the initial velocity?
`        `

a) What is the vertical component  of the initial velocity?

Ө = 45.°

` `
`Vi = 40. m/s`
`Viy = ?     `
` `
`Viy = VsinӨ`
` `
`= (40. m/s)sin45.° `

` `
`Viy = 28 m/s down `

(b) If the rock strikes ground in 1 sec what is height of cliff?

(b) If the rock strikes ground in 1.0 sec what is height of cliff?

dy = ? (height)

ay = + 9.8 m/s2

t = 1.0 sec

Viy = 28 m/s (from before)

`dy = Viyt + (˝)at2`
` `

= 28.m/s(1sec)+˝(9.8 m/s2)(1.0sec)2

`28 m + 4.9 m`
` `

` `
`dy = 32.9 m down`
` `
` `
` `
`dy = 33 m down`
` `
` `
` `
` `
` `
` `

At Peak,

Vx = ?

Vx = 9.0 m/s

Total Time in Air?

1.84 sec
(twice peak)

actually 1.8

(2 sig. figs.)

What will the horizontal velocity of the baseball be just before it hits the ground?

9 m/s, Vx is constant

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