Easy -1.8 This is a 1-mark multiple choice question testing only Newton's First Law: constant velocity means zero resultant force. Students simply equate the i-components (400 + p = 0) to get p = -400. No calculation of acceleration, no consideration of mass, and the answer is given among options—this is significantly easier than average A-level mechanics.
A particle, under the action of two constant forces, is moving across a perfectly smooth horizontal surface at a constant speed of \(10 \text{ m s}^{-1}\)
The first force acting on the particle is \((400\mathbf{i} + 180\mathbf{j})\) N.
The second force acting on the particle is \((p\mathbf{i} - 180\mathbf{j})\) N.
Find the value of \(p\).
Circle your answer.
[1 mark]
\(-400\) \quad \(-390\) \quad \(390\) \quad \(400\)
A particle, under the action of two constant forces, is moving across a perfectly smooth horizontal surface at a constant speed of $10 \text{ m s}^{-1}$
The first force acting on the particle is $(400\mathbf{i} + 180\mathbf{j})$ N.
The second force acting on the particle is $(p\mathbf{i} - 180\mathbf{j})$ N.
Find the value of $p$.
Circle your answer.
[1 mark]
$-400$ \quad $-390$ \quad $390$ \quad $400$
\hfill \mbox{\textit{AQA Paper 2 2019 Q12 [1]}}