1.8. Pressure
A subsection of Physics, 5054, through 1. Motion, forces and energy
Listing 10 of 156 questions
shows a device for punching holes in a piece of paper. A person applies a force F at the end of the arm. Just before the hole is made in the paper, the arm is at rest. paper steel rod pivot arm 1.0 cm 8.0 cm force F metal base Just before the hole is made, the force upwards on the steel rod is 7.2 N. Calculate the value of F. Use the distances marked on . F = The steel rod pushes the paper into the hole in the metal base with a force of 7.2 N. The end of the steel rod has an area of 2.8 × 10 –5 m2. Calculate the pressure exerted on the paper. State the formula that you use in your calculation. pressure = The force downwards on the paper due to the rod and the force upwards on the rod due to the paper are related by Newton’s third law. State Newton’s third law.
5054_s08_qp_2
THEORY
2008
Paper 2, Variant 0
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10 shows a car braking system. The brake fluid is an oily liquid. brake pedal master piston pivot brake drum brake shoe return spring master cylinder brake fluid slave pistons pivot The brake drum rotates with the wheel of the car. Explain how pushing the brake pedal makes the brake shoes rub against the drum. The cross-sectional area of the master piston is 2.0 cm2. A force of 140 N is applied to the master piston. Calculate the pressure created in the brake fluid by the master piston. pressure = N / cm2 The cross-sectional area of each slave piston is 2.8 cm2. Calculate the force exerted on each slave piston by the brake fluid. force = The force exerted on the master piston is greater than the force applied by the foot on the brake pedal. Using the principle of moments, explain this. shows a master cylinder sealed at one end. Instead of brake fluid, the cylinder contains air. d piston of area 2.0 cm2 sealed end air When a force is applied to the piston, the length d changes from 6.0 cm to 4.0 cm. The pressure of the air increases but the temperature stays constant. Describe how the molecules of the air exert a pressure. Explain why the pressure increases even though the temperature stays constant. The initial pressure of the air inside the cylinder is 1.0 × 105 Pa. Calculate the final pressure of the air. State the formula that you use in your calculation. pressure = Air bubbles form in the brake fluid of . State the effect this has on the braking system.
5054_s10_qp_21
THEORY
2010
Paper 2, Variant 1
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Questions Discovered
156