119k views
4 votes
A soccer ball has mass 0.40 kg. Initially it is moving to the left at 20 m/s, but then it is kicked. After the kick, it is moving at 45° upward and to the right with speed 30 m/s. Find the impulse of the net force and the average net force, assuming a collision time Δt = 0.010 s.

User Vixez
by
7.6k points

1 Answer

5 votes

The impulse of the net force is approximately \(14.14 \, \text{kg} \cdot \text{m/s}\), and the average net force is approximately \(1414 \, \text{N}\).

The impulse (\(J\)) of a force acting on an object is given by the change in momentum of the object. Mathematically, it is defined as:

\[ J = \Delta p \]

where \( \Delta p \) is the change in momentum, and \( \Delta p = m \cdot \Delta v \), where \( m \) is the mass of the object and \( \Delta v \) is the change in velocity.

1. **Calculate the change in velocity (\( \Delta v \)):**

\[ \Delta v = v_f - v_i \]

\[ \Delta v = (v_f \cdot \cos(\theta), v_f \cdot \sin(\theta)) - (v_{i_x}, v_{i_y}) \]

\[ \Delta v = (30 \cdot \cos(45^\circ) - (-20), 30 \cdot \sin(45^\circ) - 0) \]

\[ \Delta v = (30 \cdot \frac{\sqrt{2}}{2} + 20, 30 \cdot \frac{\sqrt{2}}{2}) \]

\[ \Delta v = (20\sqrt{2} + 20, 15\sqrt{2}) \]

2. **Calculate the change in momentum (\( \Delta p \)):**

\[ \Delta p = m \cdot \Delta v \]

\[ \Delta p = 0.40 \cdot (20\sqrt{2} + 20, 15\sqrt{2}) \]

\[ \Delta p = (8\sqrt{2} + 8, 6\sqrt{2}) \]

3. **Calculate the impulse (\( J \)):**

\[ J = \sqrt{(8\sqrt{2} + 8)^2 + (6\sqrt{2})^2} \]

\[ J \approx \sqrt{128 + 72} \]

\[ J \approx \sqrt{200} \]

\[ J \approx 14.14 \, \text{kg} \cdot \text{m/s} \]

4. **Calculate the average net force (\( F_{\text{avg}} \)):**

\[ F_{\text{avg}} = \frac{J}{\Delta t} \]

\[ F_{\text{avg}} = \frac{14.14}{0.010} \]

\[ F_{\text{avg}} \approx 1414 \, \text{N} \]

Therefore, the impulse of the net force is approximately \(14.14 \, \text{kg} \cdot \text{m/s}\), and the average net force is approximately \(1414 \, \text{N}\).

User Siva Cn
by
7.9k points