Measurement, Pressure and Motion

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Questions and Answers

Explain the difference between accuracy and reliability in the context of scientific measurements.

Accuracy refers to how close a measurement is to the true value, while reliability refers to the consistency or repeatability of a measurement.

In an experiment, you collect a series of mass measurements for an object: 18.96 g, 19.01 g, 19.05 g, 18.98 g, 19.34 g, and 19.04 g. Identify the anomalous reading and explain how it impacts the calculation of the mean mass.

The anomalous reading is 19.34 g. Including it will skew the mean, making it less representative of the true mass, but it should be excluded.

Describe the relationship between pressure and depth in a fluid, and explain why pressure changes with depth.

Pressure increases with depth. This is because the weight of the fluid above exerts more force on lower points.

A gas is contained within a cylinder. State two assumptions about how the gas particles move within the cylinder.

Gas particles move randomly and collide with all walls of the container. Signup and view all the answers

What is absolute zero, and how does it relate to gas pressure?

Absolute zero is the theoretical temperature at which all molecular motion stops, and a gas would exert zero pressure. Signup and view all the answers

If a car is traveling at a constant velocity of 5 m/s, what does this indicate about the forces acting on the car?

It indicates that the forces on the card are balanced. Signup and view all the answers

Explain the difference between thinking distance and braking distance in the context of stopping distances for a car.

Thinking distance is the distance traveled during the driver's reaction time before applying the brakes. Braking distance is the distance traveled once the brakes are applied until the car comes to a complete stop. Signup and view all the answers

List two factors that could cause the braking distance of a car to be increased.

Less friction, slippery road, and increase in braking distance will increase the braking distance. Signup and view all the answers

Describe an experimental procedure used to determine the spring constant of a spring.

Set up a clamp stand with a clamp and hang the spring from the clamp. Use a second clamp and boss to fix a (half) metre ruler alongside the spring. Record the metre ruler reading that is level with the bottom of the spring. Hang a 2 N weight from the bottom of the spring. Record the new position of the bottom of the spring. Calculate the extension of the spring. Signup and view all the answers

What does it mean if the line is straight on a spring graph?

The line is proportional and passes directly through the origin. Signup and view all the answers

In a circuit with a voltage source and a resistor, how are voltage, current, and resistance related? Write the equation.

Voltage is the product of current and resistance. This is described by the formula: $V = IR$ Signup and view all the answers

In a circuit, if the voltage is 12V and the current is 0.019 A, what is the resistance?

The resistance is equal to the volatge divided by the current, thus the resistance is $12 / 0.019$ Signup and view all the answers

Briefly explain how electrical energy is transferred in a wire.

Electrical energy is transferred through the collisions of the lattice ions. Signup and view all the answers

A 1400W hair dryer is connected to a 230V power supply. What current does the hair dryer draw from the power supply?

The hair dryer will draw 6.1 A, calculated as: $I = P / V = 1400 / 230 = 6.1 A$ Signup and view all the answers

Explain what the 'rate of flow of charge' means in electrical terms.

The 'rate of flow of charge' refers to current. Current is the quantity of charge passing a point in a circuit per unit of time. Signup and view all the answers

A heating element uses 13W of power and is connected to a 230V source. Calculate the energy it uses to heat something.

2990 J Signup and view all the answers

An object accelerates uniformly from rest to a certain velocity. Sketch a velocity-time graph for this motion. How can the distance traveled by the object be determined from this graph?

The graph should be a straight line with a positive slope, starting from the origin. The distance traveled is the area under the graph. Signup and view all the answers

In the context of experimental measurements, what are systematic errors, and how do they differ from random errors?

Systematic errors are consistent and repeatable errors that shift all measurements in a standardized way. Random errors are statistically random and are unpredictable. Signup and view all the answers

If the cost of electricity is 40 cents per KwH. What is the current in amps?

3.8 A Signup and view all the answers

Explain why repeating a measurement improves the reliability, but not necessarily the accuracy.

Repeating the measure gives consistency, but is not closer to the true value. Signup and view all the answers

Flashcards

Accuracy

A measure of how close a measurement is to the true value.

Reliability

A measure of the consistency or repeatability of measurements.