CIE iGCSE Co-Ordinated Science P1.5.1 Effects of forces Exam Style Questions Paper 1
▶️ Answer/Explanation
For an object to move at a constant speed in a straight line, the resultant force acting on it must be zero. This occurs when all forces are balanced. In option D, there are two equal forces (2.0 N to the right and 2.0 N to the left), which cancel each other out, giving a resultant force of zero. Therefore, object D moves at constant speed.
✅ Answer: (D)
✅ Answer: (D)
▶️ Answer/Explanation
The forces P and Q act in opposite directions along the same straight line.
The resultant force is the difference between the magnitudes: \(P – Q\) (assuming P > Q, as it is described as the larger force).
✅ Answer: (C)
The resultant force is the difference between the magnitudes: \(P – Q\) (assuming P > Q, as it is described as the larger force).
✅ Answer: (C)
▶️ Answer/Explanation
A train moving at constant speed has zero acceleration, so by Newton’s first law the resultant force on it must be zero.
Combining the two forces shown in the diagram with the air resistance force must therefore give a net force of \(0\text{ N}\).
Working through \(F_{\text{forward}} – F_{\text{other}} – F_{\text{air resistance}} = 0\) using the magnitudes in the diagram gives an air resistance force of \(40\,000\text{ N}\).
Since this force opposes the train’s motion, it must act backwards.
✅ Answer: (A)
Combining the two forces shown in the diagram with the air resistance force must therefore give a net force of \(0\text{ N}\).
Working through \(F_{\text{forward}} – F_{\text{other}} – F_{\text{air resistance}} = 0\) using the magnitudes in the diagram gives an air resistance force of \(40\,000\text{ N}\).
Since this force opposes the train’s motion, it must act backwards.
✅ Answer: (A)
▶️ Answer/Explanation
An object moving at constant speed in a straight line can have zero resultant force, so A is wrong.
Slowing down means the velocity is changing, which requires a resultant force to cause deceleration.
Forces in different directions, or of different sizes, can still combine to give a resultant, so C and D are wrong.
✅ Answer: (B)
Slowing down means the velocity is changing, which requires a resultant force to cause deceleration.
Forces in different directions, or of different sizes, can still combine to give a resultant, so C and D are wrong.
✅ Answer: (B)
▶️ Answer/Explanation
Object X has equal and opposite forces (balanced), so its resultant force is zero; objects Y and Z have unequal forces in at least one direction, producing a non-zero resultant force.
A non-zero resultant force causes acceleration (change in speed or direction) according to Newton’s Second Law \(F = ma\).
✅ Answer: (C)
A non-zero resultant force causes acceleration (change in speed or direction) according to Newton’s Second Law \(F = ma\).
✅ Answer: (C)