A crate of mass 600 kg is being pulled up a line of greatest slope of a rough plane at a constant speed of 2 m s⁻¹ by a rope attached to a winch. The plane is inclined at an angle of 30° to the horizontal and the rope is parallel to the plane. The winch is working at a constant rate of 8 kW.
- Find the coefficient of friction between the crate and the plane.[5]
Mark scheme
Marking points from the official mark scheme (Feb/Mar 2024). The mark or mark type is shown in brackets.
- [B1] Driving force = 8000/2 or 4000. Use of F = P/v, oe. E.g. DF×2=8000.
- [B1] R = 600g cos30[=3000√3=5196.152423]
- [*M1] their Driving force – 600g sin 30-F=0. For attempt to resolve parallel to the plane; 3 terms; allow sign errors; allow sin/cos mix; allow g missing; F not resolved. Allow with just DF.
- [DM1] Use of F = µR. To form an equation in u only where R is a component of weight or mass.
- [A1] µ = 0.192 or √3/9. Awrt 0.192 [0.1924500897]. Oe, e.g. 1/(3√3). Allow 2sf.
Write your answer and get it marked
On Oracle Prep you can write or photograph your own answer and have it marked by AI against this mark scheme, with feedback on what you missed.
Sign up free →