Question

A 0.500 kg football is thrown with a speed of 15.0 m/s. A stationary receiver catches the ball and brings it to rest in 0.020 s. (Take the initial direction of motion to be the positive direction.)What is the impulse delivered to the ball as it's caught?

Answer 1

Answer:

$Imp = 7.5\,\frac{kg\cdot m}{s}$

Explanation:

Let assume that direction is positive when football travels to the player. The situation can be described properly by applying the definition of Momentum and Impulse Theorem. That is to say:

$(0.5\,kg)\cdot (15\,\frac{m}{s}) - F \cdot (0.02\,s) = 0\,kg\cdot \frac{m}{s}$

The average force needed to stop is obtained after some algebraic manipulations:

$F = 375\,N$

The impulse delivered to the ball is:

$Imp = (375\,N)\cdot (0.02\,s)$

$Imp = 7.5\,\frac{kg\cdot m}{s}$

Answer 2

Answer:

Impulse delivered to the ball is 7.5Ns

Explanation:

Impulse can be defined as the product of a force and the time at which it acts.

From the queston, m = 0.5 kg, u = 15.0 m/s, t = 0.02 s and I =?

        I = F×t

But,  F = ma

          =  $\frac{mu}{t}$

          = $\frac{0.5*15}{0.02}$

          = 375N

S that,

      I = 375 × 0.02

         = 7.5

∴    Impulse delivered to the ball when caught is 7.5 Ns.