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Date May 2021 Marks available 2 Reference code 21M.2.SL.TZ2.1
Level Standard level Paper Paper 2 Time zone 2
Command term Calculate Question number 1 Adapted from N/A

Question

A football player kicks a stationary ball of mass 0.45 kg towards a wall. The initial speed of the ball after the kick is 19 m s−1 and the ball does not rotate. Air resistance is negligible and there is no wind.

The player’s foot is in contact with the ball for 55 ms. Calculate the average force that acts on the ball due to the football player.

[2]
a.

The ball leaves the ground at an angle of 22°. The horizontal distance from the initial position of the edge of the ball to the wall is 11 m. Calculate the time taken for the ball to reach the wall.

[2]
b.i.

The top of the wall is 2.4 m above the ground. Deduce whether the ball will hit the wall.

[3]
b.ii.

In practice, air resistance affects the ball. Outline the effect that air resistance has on the vertical acceleration of the ball. Take the direction of the acceleration due to gravity to be positive.

[2]
c.

The player kicks the ball again. It rolls along the ground without sliding with a horizontal velocity of 1.40m s1. The radius of the ball is 0.11m. Calculate the angular velocity of the ball. State an appropriate SI unit for your answer.

[1]
d.

Markscheme

Δp=0.45×19 OR  a =190.055  

«=F=0.45×190.055»160 «N» 

Allow [2] marks for a bald correct answer.

Allow ECF for MP2 if 19 sin22 OR 19 cos22 used.

a.

horizontal speed = 19×cos22 «=17.6 m s-1»  

time=«distancespeed=1119cos22=» 0.62«s» 

Allow ECF for MP2

b.i.

initial vertical speed=19×sin22 «= 7.1m s-1»  

«7.12×0.624-0.5×9.81×0.6242=» 2.5«m» 

ball does not hit wall OR 2.5 «m» > 2.4 «m» 


Allow ECF from (b)(i) and from MP1

Allow g = 10 m s−2

b.ii.

air resistance opposes «direction of» motion
OR
air resistance opposes velocity

on the way up «vertical» acceleration is increased OR greater than g

on the way down «vertical» acceleration is decreased OR smaller than g


Allow deceleration/acceleration but meaning must be clear

c.

13«rad»s-1


Unit must be seen for mark

Accept Hz

Accept 4 π«rad»s-1

d.

Examiners report

[N/A]
a.
[N/A]
b.i.
[N/A]
b.ii.
[N/A]
c.
[N/A]
d.

Syllabus sections

Core » Topic 2: Mechanics » 2.1 – Motion
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