Moderate -0.3 This is a standard M1 friction problem with constant velocity (equilibrium) and an angled force. It requires resolving forces in two directions and applying F=μR, but follows a completely routine method with no conceptual surprises. The 7 marks reflect the working steps rather than difficulty, making it slightly easier than average for A-level.
A suitcase of mass 40 kg is being dragged in a straight line along a rough horizontal floor at constant speed using a thin strap. The strap is inclined at \(20°\) above the horizontal. The coefficient of friction between the suitcase and the floor is \(\frac{3}{4}\). The strap is modelled as a light inextensible string and the suitcase is modelled as a particle. Find the tension in the strap.
[7]
First M1 for resolving vertically with usual rules (must be using either
20o or 70o)
First A1 for a correct equation
Second M1 for resolving horizontally with usual rules (must be using
either 20o or 70o)
Second A1 for a correct equation
B1 for seen (could be on a diagram)
Third DM1 dependent on previous two M marks
Third A1 for either 250 (N) or 246 (N)
Answer
Marks
2a
M1 A1
A1
M1A1
A1 (6)
M1A1
Answer
Marks
2b
M1 A1
M1 A1
A1 (5)
11
Notes
Answer
Marks
2a
First M1 for a moments equation or a vertical resolution
First A1 for a correct equation (R and/or R do NOT need to be
C D
substituted but if one is, it can be their value found from a previous
equation)
Second A1 for
Second M1 for a moments equation or a vertical resolution
Third A1 for a correct equation (R and/or R do NOT need to be
C D
substituted but if one is, it can be their value found from a previous
equation)
Fourth A1 for
Enter marks for equations on ePEN, in the order they appear
Answer
Marks
2b
First M1 for a moments equation or a vertical resolution
First A1 for a correct equation (R and/or R do NOT need to be
C D
substituted but if one is, it can be their value found from a previous
equation)
Second M1 for a moments equation or a vertical resolution
Second A1 for a correct equation (R and/or R do NOT need to be
C D
substituted but if one is, it can be their value found from a previous
equation)
Third A1 for
Enter marks for equations on ePEN, in the order they appear
N.B. Equations may contain any or all of R , R or x for M marks but
C D
must contain only one of R or R to earn the A mark.
C D
N.B. If they assume that R = 520, they lose all the marks for part (b).
D
N.B If they start with 2R = 1480 and then add or subtract (or both) 520
to their R value, M0.
N.B. If brackets are omitted in a moments equation e.g. (520 + R ).4 is
C
written as 520 + R .4, the M mark can be scored
C
Question 1:
1 | M1A1
M1A1
B1
Eliminate R and solve for T | DM1
T = 250 N or 246 N | A1
7
Notes
1 | First M1 for resolving vertically with usual rules (must be using either
20o or 70o)
First A1 for a correct equation
Second M1 for resolving horizontally with usual rules (must be using
either 20o or 70o)
Second A1 for a correct equation
B1 for seen (could be on a diagram)
Third DM1 dependent on previous two M marks
Third A1 for either 250 (N) or 246 (N)
2a | M1 A1
A1
M1A1
A1 (6)
M1A1
2b | M1 A1
M1 A1
A1 (5)
11
Notes
2a | First M1 for a moments equation or a vertical resolution
First A1 for a correct equation (R and/or R do NOT need to be
C D
substituted but if one is, it can be their value found from a previous
equation)
Second A1 for
Second M1 for a moments equation or a vertical resolution
Third A1 for a correct equation (R and/or R do NOT need to be
C D
substituted but if one is, it can be their value found from a previous
equation)
Fourth A1 for
Enter marks for equations on ePEN, in the order they appear
2b | First M1 for a moments equation or a vertical resolution
First A1 for a correct equation (R and/or R do NOT need to be
C D
substituted but if one is, it can be their value found from a previous
equation)
Second M1 for a moments equation or a vertical resolution
Second A1 for a correct equation (R and/or R do NOT need to be
C D
substituted but if one is, it can be their value found from a previous
equation)
Third A1 for
Enter marks for equations on ePEN, in the order they appear
N.B. Equations may contain any or all of R , R or x for M marks but
C D
must contain only one of R or R to earn the A mark.
C D
N.B. If they assume that R = 520, they lose all the marks for part (b).
D
N.B If they start with 2R = 1480 and then add or subtract (or both) 520
to their R value, M0.
N.B. If brackets are omitted in a moments equation e.g. (520 + R ).4 is
C
written as 520 + R .4, the M mark can be scored
C
A suitcase of mass 40 kg is being dragged in a straight line along a rough horizontal floor at constant speed using a thin strap. The strap is inclined at $20°$ above the horizontal. The coefficient of friction between the suitcase and the floor is $\frac{3}{4}$. The strap is modelled as a light inextensible string and the suitcase is modelled as a particle. Find the tension in the strap.
[7]
\hfill \mbox{\textit{Edexcel M1 2017 Q1 [7]}}