1.5.5. Turning effect of forces
A subsection of Physics, 5054, through 1. Motion, forces and energy
Listing 10 of 30 questions
When the lid of a freezer is opened, it pivots about the hinge at the back of the freezer. The handle is at the front. is a side view of the freezer. lid lid handle 0.70 m hinge F The handle is 0.70 m from the hinge. The lid has a mass of 2.0 kg. The gravitational field strength g is 10 N / kg. Calculate the weight of the lid. weight = The lid is uniform and its centre of mass is at its centre. The weight of the lid produces a moment about the hinge. 1. Calculate the moment about the hinge when the lid is closed. moment = 2. The moment required to open the lid is greater than the value calculated in 1. Suggest one reason for this. The lid is closed. To open the lid, a force F is applied to the handle as shown in . The direction of F is vertically upwards and F is the smallest possible force that opens the lid. A force on the handle in any other direction must be larger than F in order to open the lid. Explain why.
5054_w16_qp_22
THEORY
2016
Paper 2, Variant 2
View
shows a painter standing on a wooden plank, directly above the right-hand support. 3.6 m 1.3 m 0.025 m 0.35 m support centre of mass wooden plank support The plank has length 3.6 m, width 0.35 m and thickness 0.025 m. The gravitational field strength g is 10 N / kg and the mass of the plank is 23 kg. Calculate the density of the wood from which the plank is made. density = The centre of mass of the plank is in the middle of the plank at a distance of 1.3 m from each of the supports. Calculate the weight of the plank, weight = the moment of the plank about the right-hand support. moment = The painter moves further to the right along the plank and the plank rotates about the right- hand support. Explain why the plank rotates.
5054_w17_qp_21
THEORY
2017
Paper 2, Variant 1
View
shows a model of the human arm. The rubber band represents the muscle that moves part of the arm XY up. A mass is suspended from XY, as shown in . The weight of section XY is negligible and the model is at rest. rubber band pivot X Y X Y rubber band pivot 2.0 cm 16 cm mass (not to scale) State two ways in which the dimensions of the rubber band change as the mass is added to section XY. State the form of energy stored in the stretched rubber band. State the principle of moments. Explain why the force that the rubber band exerts on section XY is larger than the weight of the mass. The mass suspended from section XY in has a weight of 4.0 N. Calculate the force that the rubber band exerts on section XY. force = Explain how your answer to is different if the weight of section XY is not negligible.
5054_s22_qp_21
THEORY
2022
Paper 2, Variant 1
View
shows a bed that folds away against a wall during the day. wall hinge bed 0.35 m 0.30 m leg W (not to scale) When it is horizontal, the bed is supported on one side by a hinge and on the other side by two legs. The weight W of the bed acts through its centre of mass, which is at a horizontal distance of 0.35 m from the hinge. The mass of the bed is 26 kg. The gravitational field strength g is 10 N / kg. Calculate the weight W of the bed. W = State the principle of moments. Determine the size of the total upward force exerted on the bed by the two legs when the bed is horizontal. total force =
5054_w16_qp_21
THEORY
2016
Paper 2, Variant 1
View
Questions Discovered
30