Moderate -0.8 This is a straightforward application of the power-force-velocity relationship (P = Fv) to find driving force, followed by Newton's second law (F = ma). It requires only standard recall of formulas and simple algebraic manipulation with no problem-solving insight needed, making it easier than average but not trivial due to the two-step process.
A car of mass 800 kg moves in a straight line along a horizontal road.
There is a constant resistance to the motion of the car of magnitude 600 N.
When the car is travelling at a speed of \(15 \text{ m s}^{-1}\) the power developed by the car is 27 kW.
Determine the acceleration of the car when it is travelling at \(15 \text{ m s}^{-1}\). [4]
D) – condone sign errors but must be correct mass of
800 (so dimensionally consistent)
Answer
Marks
Guidance
a = 1 .5 (m s-2)
A1
1.1
[4]
Question 1:
1 | 1 5 D 2 7 0 0 0 | M1 | 1.1 | Use of P = Dv with P = 27000 or 27
2 7 0 0 0
D = 1 8 0 0 (N) or
1 5 | A1 | 1.1 | Or implied by later working
D − 6 0 0 = 8 0 0 a | M1 | 3.3 | N2L – correct number of terms with their D (or just
D) – condone sign errors but must be correct mass of
800 (so dimensionally consistent)
a = 1 .5 (m s-2) | A1 | 1.1
[4]
A car of mass 800 kg moves in a straight line along a horizontal road.
There is a constant resistance to the motion of the car of magnitude 600 N.
When the car is travelling at a speed of $15 \text{ m s}^{-1}$ the power developed by the car is 27 kW.
Determine the acceleration of the car when it is travelling at $15 \text{ m s}^{-1}$. [4]
\hfill \mbox{\textit{OCR MEI Further Mechanics Major 2023 Q1 [4]}}