7 (a) Figure 16 shows part of the inside of a pen - Edexcel - GCSE Physics - Question 7 - 2023 - Paper 2

The student can determine the change in length of the spring by following these steps:

1. Initial Measurement: Position the spring vertically and note the initial length (use the ruler).
2. Compression Measurement: Gently press down on the spring and record the new length while noting the position of the top of the spring against the ruler.
3. Calculate Change: Subtract the compressed length from the initial length to find the change. For example:
   • If the initial length is 3.0 cm and the pressed length is 2.1 cm, then:
   • Change in length = $3.0 \text{ cm} - 2.1 \text{ cm} = 0.9 \text{ cm}.$

To improve the procedure, the student could use a pointer or a reference mark to accurately mark the initial position of the spring. This would help minimize parallax error and ensure better accuracy when measuring the length of the spring before and after compression.

The force exerted on the top of the spring by the hook can be calculated by adding the weight of the block to the weight of the spring. The total weight is:

• Weight of the spring = 1 N
• Weight of the block = 5 N

Total force exerted upwards = $5 + 1 = 6 \, N$.

So the correct answer is:

C 6 N down.

To complete the diagram:

1. Forces Given: P = 30 N acting downwards and Q = 40 N acting horizontally to the right.

2. Resultant Force (R): Use the Pythagorean theorem to find the magnitude of R:

   $R = \sqrt{(30)^2 + (40)^2} = \sqrt{900 + 1600} = \sqrt{2500} = 50 \, N$

3. Direction of R: R should be drawn diagonally from point X to depict the resultant force direction, which can be calculated using Trigonometry if needed (find angle if necessary).

Indicate this force with an arrow labeled R in the appropriate direction on the diagram.