# Forces 1 - vectors, resultant forces and work

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9 reviews
Last updated: 15/11/2023
Contributor: Teachit Author
Main Subject
Key stage
Exam board
Category
Forces: Forces and motion
Inside
Resource type
Revision
Starter/Plenary
Student activity

A KS4 physics resource with a set of 14 challenging multiple-choice forces questions, complete with comprehensive answers. Use the paper version for an exam-style worksheet where students can record their workings and answers, or use the PowerPoint for a quick class quiz. To further stretch students, try the follow-on resource Forces 2 – vectors, resultant forces and work.

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I note that you have decided to leave question 1 as it is rather than amend it in response to the review pointing out the problem with it. I feel that it should be amended, because as it stands it reinforces the intuitive but incorrect idea that objects slow down and stop unless a force is applied.

Ruth Campbell

19/09/2023

Response from Teachit editor
Question 1 has been amended to ask which situation would cause the ball to have the greatest acceleration. The question now specifies that the force is instantaneous. The following note has also been added: For the sake of simplicity, friction has not been included in the calculations, but you might want to point out to students that without it the balls would continue at a constant speed forever.
Question 15 is impossible to answer, and the answer given contains two serious misconceptions.
The answer to question 15 says that the work done by the target on the bullet must be equal to the work done by the bullet in travelling to the target. This is mistaken as there is no reason for these to be equal. The answer then goes on to calculate this work done as the weight of the bullet multiplied by the distance travelled by the bullet. The weight of the bullet and the direction moved by the bullet are likely to be approximately perpendicular to each other, so this is forgetting that work done = force x distance moved in the direction of the force. A better question would be to ask what was the velocity of the bullet when it hit the target, as then you could equate the work done in stopping the bullet to the kinetic energy of the bullet as it hit the target.

Ruth Campbell

19/09/2023

Response from Teachit editor
Thank you for your feedback, Ruth. We're looking to get this corrected. In the meantime, we've removed question 15 from the resource.

21/05/2020

23/03/2019

I note that you have decided to leave question 1 as it is rather than amend it in response to the review pointing out the problem with it. I feel that it should be amended, because as it stands it reinforces the intuitive but incorrect idea that objects slow down and stop unless a force is applied.

Ruth Campbell

19/09/2023

Response from Teachit editor
Question 1 has been amended to ask which situation would cause the ball to have the greatest acceleration. The question now specifies that the force is instantaneous. The following note has also been added: For the sake of simplicity, friction has not been included in the calculations, but you might want to point out to students that without it the balls would continue at a constant speed forever.
Question 15 is impossible to answer, and the answer given contains two serious misconceptions.
The answer to question 15 says that the work done by the target on the bullet must be equal to the work done by the bullet in travelling to the target. This is mistaken as there is no reason for these to be equal. The answer then goes on to calculate this work done as the weight of the bullet multiplied by the distance travelled by the bullet. The weight of the bullet and the direction moved by the bullet are likely to be approximately perpendicular to each other, so this is forgetting that work done = force x distance moved in the direction of the force. A better question would be to ask what was the velocity of the bullet when it hit the target, as then you could equate the work done in stopping the bullet to the kinetic energy of the bullet as it hit the target.

Ruth Campbell

19/09/2023

Response from Teachit editor
Thank you for your feedback, Ruth. We're looking to get this corrected. In the meantime, we've removed question 15 from the resource.

21/05/2020

23/03/2019

04/03/2019

Many thanks for your comments. We've left the question as it on the PowerPoint, but your comment does highlight a really important teaching point for others to use with their classes.

Sarah Kniveton, Science Editor

14/09/2017

I am planning to use this to review last year's work with my Y11 class. I really like the look of this resource and the level of challenge. One tiny edit I would suggest is the texts on slide 2 to be: "1. Which of the following situations of forces acting on a ball would cause the ball to have the greatest acceleration?" at the top and "D. has the greatest resultant force, 20 N, accelerating the ball to the left with the greatest acceleration." at the bottom of the slide; however, I do accept that D will move the furthest, assuming that the forces are all applied for the same amount of time, so the original texts work, my suggestion is just to emphasise the connection between resultant force and acceleration. Many thanks for a really good resource!

12/09/2017

To revise for my son in y7

04/02/2017