Bernoulli's Principle - Spin

Question 1

What is Bernoulli’s principle?

Answer 1

States the velocity of a fluid moving over an object is inversely proportional to the pressure on the object. When the velocity of a fluid moving over an object increases it creates a low pressure system.

Question 2

Draw a labelled diagram of a javelin in the air.

Answer 2

Did you include -
1. Low pressure/high velocity on top.
2. High pressure/low velocity on the bottom.
3. The angle of release (47 degrees)
4. The direction of airflow.
5. The direction of the javelin.
6. The lift force.

Question 3

What is the magnus effect?

Answer 3

Is used to describe the effect of rotation on an objects flight path as it moves through a fluid. The pressure differential high on one side and low on the other, creates a lift force that causes the ball to move in the direction of the pressure differential.

Question 4

What are the 2 types of spin?

Answer 4

1. Backspin.
2. Topspin.

Question 5

What is backspin?

Answer 5

Creating backspin will ensure the ball travels a maximum distance.

Question 6

What is top spin?

Answer 6

Allows the ball to be hit harder with a higher velocity. Top spin causes the ball to bounce of the surface with a lower angle making it harder to return.

Question 7

Draw a labelled diagram which demonstrates the effect spin has on the trajectory of a ball.

Answer 7

Y axis - height (m)
X axis - Distance (m)
Backspin travels the furthest.
Top spin travels the least.
No spin travels further than top spin but less than back spin.

Question 8

Draw a labelled diagram of a ball that is hit with backspin.

Answer 8

1. Eccentric force applied (contact)
2. Direction of spin.
3. High pressure/low velocity below - at contact of the ball.
4. Low pressure/high velocity at the top of the ball.
5. Direction of lift (magnus effect)
6. The direction of the ball.
7. The direction of airflow.

Question 9

Draw a labelled diagram of a ball that is hit with top spin.

Answer 9

1. Eccentric force applied (contact)
2. Direction of spin.
3. High pressure/low velocity below - at contact of the ball.
4. Low pressure/high velocity at the bottom of the ball.
5. Direction of lift (magnus effect)
6. The direction of the ball.
7. The direction of airflow.

Question 10

Using Bernoulli’s principle explain what happens with a ball hit with backspin.

Answer 10

An eccentric force is applied below the centre of the ball. Airflow around the spinning ball (boundary layer) going in the same direction as oncoming air creates high velocity. Areas of high velocity form a low-pressure system. Airflow around the spinning ball (boundary layer) going in the opposite direction as oncoming air creates low velocity. Areas of low velocity form a high-pressure system. Air moves from an area of high pressure to an area of low pressure creating the Magnus force.

Question 11

Using Bernoulli’s principle explain what happens with a ball hit with top spin.

Answer 11

An eccentric force is applied above the centre of the ball. On the bottom side of the ball, airflow around the spinning ball (boundary layer) is going in the same direction as oncoming air creating high velocity. Areas of high velocity form a low-pressure system on the bottom of the ball. On the top side of the ball, airflow around the spinning ball (boundary layer) is going in the opposite direction as oncoming air creating low velocity. Areas of low velocity form a high-pressure system on top of the ball. Air moves from an area of high pressure to an area of low pressure creating the Magnus force.