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Question 19N.2.SL.TZ0.1

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Date November 2019 Marks available [Maximum mark: 9] Reference code 19N.2.SL.TZ0.1
Level SL Paper 2 Time zone TZ0
Command term Calculate, Determine, Draw, Show that Question number 1 Adapted from N/A
1.
[Maximum mark: 9]
19N.2.SL.TZ0.1

The graph shows the variation with time t of the horizontal force F exerted on a tennis ball by a racket.

The tennis ball was stationary at the instant when it was hit. The mass of the tennis ball is 5.8 × 10–2 kg. The area under the curve is 0.84 N s.

(a)

Calculate the speed of the ball as it leaves the racket.

[2]

Markscheme

links 0.84 to Δp ✔

v=«0.845.8×10-2=» 14.5 «m s–1»✔

NOTE: Award [2] for bald correct answer

(b)

Show that the average force exerted on the ball by the racket is about 50 N.

[2]

Markscheme

use of Δt = «(28 – 12) × 10–3 =» 16 × 10–3 «s» ✔

F¯ =«∆p∆t=» 0.8416×10-3 OR  53 «N» ✔

NOTE: Accept a time interval from 14 to 16 ms
Allow ECF from incorrect time interval

(c)

Determine, with reference to the work done by the average force, the horizontal distance travelled by the ball while it was in contact with the racket.

[3]

Markscheme

Ek = 12 × 5.8 × 10–2 × 14.52 ✔

Ek = W ✔

s = «WF=12×5.8×10-2×14.5253=» 0.12 « m » ✔

 

Allow ECF from (a) and (b)

Allow ECF from MP1

Award [2] max for a calculation without reference to work done, eg: average velocity × time

(d)

Draw a graph to show the variation with t of the horizontal speed v of the ball while it was in contact with the racket. Numbers are not required on the axes.

[2]

Markscheme

graph must show increasing speed from an initial of zero all the time ✔
overall correct curvature ✔

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