Posted by **Anonymous** on Friday, October 5, 2012 at 1:14am.

4. A football player passes the ball. The ball leaves his hand and is caught 1.7 seconds later by a receiver 30 meters away. (You may assume the ball was caught at the same height from which it was thrown.)

a) What is the vertical component of the velocity of the ball just after it is released?

b) What is the speed (the magnitude of the velocity) of the ball when it is at the top of its trajectory?

c) What is the speed (the magnitude of the velocity) of the ball just before it is caught?

- Physics -
**Jennifer**, Friday, October 5, 2012 at 9:43am
vx(t) = vx0

vy(t) = vy0 - g*t

y = vy0*t - 1/2*g*t^2

x = vx0*t

where y is vertical distance measured from the height of the football player's hand, x is the horizontal distance, t is time, vy0 is the initial speed in the y direction, vx0 is the initial speed in the x direction, and vy(t) is the speed in the y direction as a function of time, and vx(t) is the speed in the x direction as a function of time

When the football player catches the ball at 1.7s, the vertical height y is back at 0, and the horizontal distance is at 30

0 = vy0*1.7 - 1/2*g*1.7^2

30 = vx0*1.7

Solve for vy0 and vx0

a) The vertical component of the velocity of the ball just after it is released is vy(t) evaluated at t = 0

vy(t) = vy0

b) At the top of its trajectory, the ball will be exactly halfway to the receiver, so t = 1.7/2 = 0.85 s. At this time

vy(t) = vy0 - g*0.85

vx(t) = vx0

solve

then the magnitude of the speed is

(vy(t)^2 + vx(t)^2)^0.5

c) Just before the ball is caught, t = 1.7s

vy(t) = vy0 - g*1.7

vx(t) = vx0

solve for vy(t) and vx(t), and then use the formula from part b to calculate the magnitude of the vector

## Answer this Question

## Related Questions

- Dynamics - A quarterback throws a football with a velocity vo at an angle of 45o...
- Physics - A quarterback is asked to throw a football to a receiver that is 32.6 ...
- physics - A quarterback is asked to throw a football to a receiver that is 32.1 ...
- physics - PLEASE I HAVE NO IDEA WHERE TO START A quarterback is asked to throw a...
- Physics - A 0.60kg basketball is dunked vertically downward so that it leaves ...
- Physics - A 0.60kg basketball is dunked vertically downward so that it leaves ...
- algebra 2 - a baseball player hits a fly ball that is caught about 5 seconds ...
- Physics - A batter hits a ball and it is caught 4 seconds later 100 meters from ...
- cjc - Science A batsman hits a cricket ball from ground level. It is caught 1.8 ...
- Physics - A quarterback throws a pass at an angle of 40 degrees above the ...

More Related Questions