| Exam Board | AQA |
|---|---|
| Module | M1 (Mechanics 1) |
| Year | 2013 |
| Session | June |
| Marks | 17 |
| Paper | Download PDF ↗ |
| Topic | Newton's laws and connected particles |
| Type | Block on rough horizontal surface – accelerating (finding acceleration or applied force) |
| Difficulty | Moderate -0.3 This is a standard M1 friction problem requiring resolution of forces, use of F=μR, and Newton's second law. Part (a) involves routine calculations with given tension, part (b) requires finding tension for constant velocity (a=0), and part (c) tests conceptual understanding that friction is independent of speed. All techniques are textbook-standard with no novel problem-solving required, making it slightly easier than average. |
| Spec | 3.03f Weight: W=mg3.03t Coefficient of friction: F <= mu*R model3.03u Static equilibrium: on rough surfaces3.03v Motion on rough surface: including inclined planes |
7 A block of mass 30 kg is dragged across a rough horizontal surface by a rope that is at an angle of $20 ^ { \circ }$ to the horizontal. The coefficient of friction between the block and the surface is 0.4 .
\begin{enumerate}[label=(\alph*)]
\item The tension in the rope is 150 newtons.
\begin{enumerate}[label=(\roman*)]
\item Draw a diagram to show the forces acting on the block as it moves.
\item Show that the magnitude of the normal reaction force on the block is 243 newtons, correct to three significant figures.
\item Find the magnitude of the friction force acting on the block.
\item Find the acceleration of the block.
\end{enumerate}\item When the block is moving, the tension is reduced so that the block moves at a constant speed, with the angle between the rope and the horizontal unchanged. Find the tension in the rope when the block is moving at this constant speed.
\item If the block were made to move at a greater constant speed, again with the angle between the rope and the horizontal unchanged, how would the tension in this case compare to the tension found in part (b)?
\end{enumerate}
\hfill \mbox{\textit{AQA M1 2013 Q7 [17]}}