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Questions and Answers
Force is a scalar quantity.
False
The S.I. unit of velocity is meter per second squared.
False
Friction is a type of contact force.
True
Gravity is an example of a contact force.
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Lift is a type of air resistance.
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The slope of a distance-time graph represents velocity.
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Newton's second law of motion relates force, mass, and velocity.
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The work input is always equal to the work output in a machine.
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A girl walks 200m N, then 300m W then 150m N, then 200m E, then 100m N, then 100m E. The displacement of the girl is zero.
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A car passes a cyclist traveling at 15m/s, from the frame of reference of the cyclist, the car appears to be traveling at 7m/s.
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A naughty boy running west at 4m/s on a people mover moving east at 1.5m/s has a velocity relative to a person standing on the carpeted floor of 2.5m/s west.
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346cm is equal to 3.46m.
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A car accelerating from 0 to 15m/s in 30 seconds has an acceleration of 0.5m/s^2.
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If acceleration is zero, velocity must also be zero.
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A runner completing an 800 meter race in 90 seconds has an average speed of 8.89m/s.
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Gravity is not a type of friction.
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Momentum is a product of an object's mass and velocity. Since the velocity is zero, the momentum is also zero.
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A velocity vs. time graph of a car traveling down the street appearing as a straight line sloping upwards indicates that the car's acceleration is constant.
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A jaguar accelerating from 0 to 10.3m/s in 3.0 seconds has an acceleration of 3.43m/s^2.
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The force that opposes your push when you're unable to move an object is gravity.
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Air resistance is the force that acts on a projectile besides gravity.
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Mass and weight are exactly the same thing.
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Rolling friction is always greater than static friction.
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Objects in free fall eventually reach a constant velocity due to air resistance.
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If the input force of a machine is less than the output force, then the input distance is greater than the output distance.
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A fixed pulley is an example of a compound machine.
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The force exerted by the tab to open a soda can is greater than the force applied by the person to the tab.
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A screwdriver is an example of a lever.
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A wheel chair ramp is an example of an inclined plane.
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A nutcracker is an example of a wedge.
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The force required to push a full shopping cart is less than the force required to push an empty one due to Newton's third law.
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The acceleration of a 0.2 kg baseball thrown with a force of 30N is 150 m/s^2.
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A WWF wrestler with a mass of 157 kg weighs approximately 1550 N.
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The momentum of a 4.7 g bullet shot from a gun at 1600 m/s is greater than the momentum of a baseball with a mass of 150g thrown at 39m/s.
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The reaction force in a balloon car is the force exerted by the air molecules on the balloon.
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Bernoulli's principle states that the pressure of a fluid decreases as its velocity increases.
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The buoyancy force on an object is equal to its weight when it is suspended.
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Study Notes
Physics Exam Study Guide
Terms and Concepts
- Vector vs Scalar Quantity:
- Vector: has magnitude and direction
- Scalar: has only magnitude
- Motion:
- Frame of Reference: a fixed point from which motion is measured
- Distance vs Displacement:
- Distance: total length of path traveled
- Displacement: shortest distance between initial and final positions
- Speed vs Velocity:
- Speed: scalar quantity, rate of change of distance
- Velocity: vector quantity, rate of change of displacement
- Instantaneous Speed vs Average Speed:
- Instantaneous Speed: speed at a specific point in time
- Average Speed: total distance traveled divided by time
- Distance vs Time Graphs:
- Slope of the graph represents velocity
- Acceleration:
- Rate of change of velocity
- Can be calculated using the formula: a = Δv / Δt
- Velocity vs Time Graphs:
- Slope of the graph represents acceleration
- Force:
- Push or pull that causes an object to change its motion
- Newton's Laws of Motion:
- First Law: Inertia, an object at rest stays at rest, an object in motion stays in motion
- Second Law: F = ma, force is equal to mass times acceleration
- Third Law: Every action has an equal and opposite reaction
- Work and Energy:
- Work: force applied over a distance
- Energy: ability to do work
- Machines:
- Simple Machines: lever, pulley, wheel and axle, inclined plane, wedge, screw
- Compound Machines: combination of simple machines
- Momentum:
- Product of an object's mass and velocity
- Pressure:
- Force per unit area
- Bernoulli's Principle:
- Faster moving fluids have lower pressure, slower moving fluids have higher pressure
- Buoyancy and Buoyancy Force:
- Upward force exerted on an object by a fluid (liquid or gas)
- Archimedes' Principle: buoyancy force is equal to the weight of the fluid displaced
- Friction:
- Force that opposes motion between two surfaces in contact
- Types: static, sliding, rolling, fluid
Formulas
- Average Velocity or Speed:
- v_avg = Δx / Δt
- Average Acceleration:
- a_avg = Δv / Δt
- Acceleration:
- a = F / m (Newton's Second Law)
- Weight:
- W = mg (mass times acceleration due to gravity)
- Momentum:
- p = mv (mass times velocity)
- Pressure:
- P = F / A (force per unit area)
- Work:
- W = F × d (force times distance)
- Power:
- P = W / t (work divided by time)
Review Questions
- Questions 1-44: various physics concepts and problems
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Description
Review key physics concepts for 8th grade science exam, including vector and scalar quantities, motion, distance, speed, velocity, acceleration, and graph interpretation.
