Question 2
2
Question 2(a)
2(a)
Define
Question 2(a)(i)
2(a)(i)
force,
Answer
force is rate of change of momentum
Question bank
A-Level CAIE Physics 4 1 Turning Effects Of Forces Question Bank
Practice A-Level CAIE Physics 4 1 Turning Effects Of Forces questions by syllabus topic with past-paper context, marks, difficulty and question previews on Eduninja.
Question 2
2
A large bowl is made from part of a hollow sphere. A small spherical ball is placed inside the bowl and is given a horizontal speed. The ball follows a horizontal circular path of constant radius, as shown in Fig. 2.1. The forces acting on the ball are its weight W and the normal reaction force R of the bowl on the ball, as shown in Fig. 2.2. The normal reaction force R is at an angle \(\theta\) to the horizontal.
Question 2(a)
2(a)
Question 2(a)(i)
2(a)(i)
By resolving the reaction force R into two perpendicular components, show that the resultant force F acting on the ball is given by the expression
Answer
\(F=R \cos \theta\) M1 \(W=R \sin \theta\) M1 dividing, \(W=F \tan \theta\) A0 (max. 1 if derivation to final line not shown)
Question 2
2
A large bowl is made from part of a hollow sphere. A small spherical ball is placed inside the bowl and is given a horizontal speed. The ball follows a horizontal circular path of constant radius, as shown in Fig. 2.1. The forces acting on the ball are its weight W and the normal reaction force R of the bowl on the ball, as shown in Fig. 2.2. The normal reaction force R is at an angle \(\theta\) to the horizontal.
Question 2(a)
2(a)
Question 2(a)(i)
2(a)(i)
By resolving the reaction force R into two perpendicular components, show that the resultant force F acting on the ball is given by the expression
Answer
\(W=R \sin \theta\) dividing, \(W=F \tan \theta\) (max. 1 if derivation to final line not shown)
Question 2
2
Question 2(a)
2(a)
Define the torque of a couple.
Answer
torque is the product of one of the forces and the distance between forces M1 the perpendicular distance between the forces A1 [2]
Question 2(b)
2(b)
A uniform rod of length 1.5 m and weight 2.4 N is shown in Fig. 2.1. The rod is supported on a pin passing through a hole in its centre. Ropes A and B provide equal and opposite forces of 8.0 N .
Question 2(b)(i)
2(b)(i)
Calculate the torque on the rod produced by ropes A and B .
Answer
torque \(=8 \times 1.5=12 \mathrm{Nm} \quad\) A1 [1]
Question 2
2
Question 2(a)
2(a)
State what is meant by the centre of gravity of an object.
Answer
the point where (all) the weight (of the object) is taken to act B1
Question 2
2
Question 2(a)
2(a)
State what is meant by the centre of gravity of an object.
Answer
point where (all) the weight (of the object) is taken to act B1
Question 2(c)
2(c)
The sphere in (b) is now immersed in a liquid in a container, as shown in Fig. 2.2. The density of the liquid is \(1100 \mathrm{~kg} \mathrm{~m}^{-3}\). The upthrust acting on the sphere due to the liquid is 2.5 N . The magnitude of F is unchanged so that the horizontal rod is not in equilibrium.
Question 2(c)(ii)
2(c)(ii)
Calculate the magnitude and direction of the resultant moment of the forces on the rod about P. magnitude of resultant moment = Nm direction of resultant moment
Answer
resultant moment \(=2.5 \times 2.9\) \[ =7.3 \mathrm{~N} \mathrm{~m} \] or resultant moment \(=F \times 1.1-(44 \times 0.6+0.5 \times 2.9)\) =7.3 Nm (allow 7.2 Nm or 7.4 Nm from rounded values of F ) A1 direction: anticlockwise A1
Question 10
10
The diagram shows the view from above of a sprinkler system used to water a garden. The sprinkler consists of a tube of length 0.15 m . The tube is pivoted in the middle and spins in a horizontal plane as it lets out jets of water from each end. The two water jets are in opposite directions to each other. Each water jet exerts a horizontal force of 3.0 N on the tube at right angles to the tube. What is the magnitude of the torque on the tube from the water jets? 0 Nm 0.23 Nm 0.45 Nm 0.90 Nm
Answer
C
Question 10
10
A perfectly elastic collision occurs between two objects X and Y . The mass of X is m and the mass of Y is 4 m. Object X travels at speed v before the collision and speed \(\frac{3 v}{5}\) in the opposite direction after the collision. Object Y is stationary before the collision. after What is the kinetic energy of Y after the collision? \(\frac{8}{10} m v^{2}\) \(\frac{34}{50} m v^{2}\) \(\frac{16}{50} m v^{2}\) \(\frac{1}{5} m v^{2}\)
Answer
C
Question 11
11
Two forces act on an object. Which diagram represents a couple?
Answer
B
Question 3
3
Question 3(a)
3(a)
State what is meant by the centre of gravity of a body.
Answer
point at which (whole) weight (of body) (allow mass for weight) M1 appears / seems to act ... (for mass need 'appears to be concentrated') A1 [2]
Question 3(b)
3(b)
A uniform rectangular sheet of card of weight W is suspended from a wooden rod. The card is held to one side, as shown in Fig. 3.1. On Fig. 3.1,
Question 3(b)(i)
3(b)(i)
mark, and label with the letter C , the position of the centre of gravity of the card,
Answer
point C shown at centre of rectangle \(\pm 5 \mathrm{~mm} \quad\) B1 [1]
Question 3(b)(ii)
3(b)(ii)
mark with an arrow labelled W the weight of the card.
Answer
arrow vertically downwards, from C with arrow starting from the same margin of error as in (b)(i) B1 [1]