# Impulse of Punt Homework: Mass Needed?

• kq6up
In summary, the conversation discusses the impulse delivered by a punter's foot when kicking a ball. The conversation goes on to mention the need for the mass of the ball in order to calculate the impulse, and provides a solution for the magnitude and direction of the impulse. One participant also points out a typographical error in the calculation.
kq6up

## Homework Statement

A punter drops a ball from rest vertically 1 meter down onto his foot. The ball leaves the foot with a speed of 18m/s at an angle of 55##^{\circ}## above the horizontal. What is the impulse delivered by the foot (magnitude and direction)?[/B]

## Homework Equations

##p_b+p_f=p^{\prime}_{b}+p^{\prime}_{f}##
##v^2=v_{o}^2+2gh##

## The Attempt at a Solution

##\sqrt{2gh}=4.43m/s##

Would not one need to know the mass of the football to solve this problem? I find it uncomfortable and strange that the mass of the football is not included in this problem. Am I correct in this assertion?

Thanks,
KQ6UP
[/B]

Yes, you need the mass in order to get a numerical value for the magnitude of the impulse. You might have to settle for specifying the answer in terms of the mass.

kq6up
You can Google for the mass of a regulation football. (0.40 to 0.43 kg).

kq6up
Ok, I used .43kg, and I get:
##v=\sqrt{2gh}## implies that ##v=4.43m/s##.

I used ##I=\Delta \boldsymbol{P}=\boldsymbol{P}-\boldsymbol{P}_o##

Then componentized:

##\boldsymbol{P}_o=-1.90kg\cdot m/s \cdot \hat{y}##

##\boldsymbol{P}=18 m/s \cdot .43 kg \cdot (\cos 55^o \hat{y}+\sin 55^o \hat{x})##

##\therefore## ##\Delta \boldsymbol{P}## is a vector pointing 61.7##^o## with a magnitude of 9.36##kg \cdot m/s##. Is this correct?

Thanks,
KQ6UP

Last edited:
Your answer looks correct. There appears to be a typographical error where your unit vectors ##\hat{x}## and ##\hat{y}## need to switch places in the expression for P.

TSny said:
Your answer looks correct. There appears to be a typographical error where your unit vectors ##\hat{x}## and ##\hat{y}## need to switch places in the expression for P.

Yes, that is a typo. Thanks,

KQ6UP

Here it is fixed for the record.

kq6up said:
Ok, I used .43kg, and I get:
##v=\sqrt{2gh}## implies that ##v=4.43m/s##.

I used ##I=\Delta \boldsymbol{P}=\boldsymbol{P}-\boldsymbol{P}_o##

Then componentized:

##\boldsymbol{P}_o=-1.90kg\cdot m/s \cdot \hat{y}##

##\boldsymbol{P}=18 m/s \cdot .43 kg \cdot (\cos 55^o \hat{x}+\sin 55^o \hat{y})##

##\therefore## ##\Delta \boldsymbol{P}## is a vector pointing 61.7##^o## with a magnitude of 9.36##kg \cdot m/s##. Is this correct?

Thanks,
KQ6UP

## 1. What is the "Impulse of Punt Homework"?

The "Impulse of Punt Homework" refers to a physics concept that involves calculating the impulse, or change in momentum, of an object during a punt in American football. This calculation takes into account factors such as the mass and velocity of the ball, as well as the time and force of impact.

## 2. Why is it important to calculate the impulse of a punt?

Calculating the impulse of a punt allows us to understand the amount of force that is applied to the ball and the resulting change in its momentum. This can help coaches and players make strategic decisions about kicking and receiving punts, as well as provide insight into the physical principles at play in the sport.

## 3. How is the mass needed for a punt calculated?

The mass needed for a punt is calculated by using the formula:

Mass = Impulse / Velocity

This means that the mass is equal to the impulse (force x time) divided by the velocity of the ball. This calculation can be used to determine the ideal mass for a punt to achieve a desired velocity.

## 4. What other factors besides mass affect the impulse of a punt?

In addition to mass, other factors that affect the impulse of a punt include the force applied by the kicker, the time of impact, and the velocity of the ball. The angle and direction of the kick can also play a role in the resulting impulse.

## 5. How can the impulse of a punt be applied to other areas of science?

The concept of impulse can be applied to many areas of science, including engineering, mechanics, and sports science. Understanding the relationship between force, time, and velocity can help in designing and analyzing various systems and phenomena, such as the motion of projectiles or the impact of collisions.

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