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Conceptual Physics Exam 1 fall 2007 Formulas
Velocity acquired in free fall, from rest; Distance fallen in free fall, from rest; Speed and Velocity Speed rate of change of position or distance covered divided of time required to cover this distance.
Know how to solve simple problems using these relations. Speed is relative.
We are moving with respect to the Sun at 30 kilometers per second and
the surface of the Earth is moving due to rotations at about 700 miles per
hour in Velocity combines the speed of an object with the direction of travel. Vectors - Velocity is often shown graphically as an arrow whose length is the speed and pointing in the direction of travel. Resultants of vectors - The collective effect of several vectors (i.e. velocities here). Vectors can be combined graphically by drawing the parallelograms.
60 km/hr Acceleration rate of change of velocity change, or change in velocity divided by time required for the change.
Accelerations can cause changes in magnitude or direction of a velocity. Distances and accelerations:
Acceleration due to gravity, g, is constant for objects of different masses and is about 10 meters per second First Law Every material object continues a constant state of rest, or of uniform motion, (velocity) in a straight line, unless it is compelled to change that state of motion by forces acting upon it. Inertial the property of bodies to resist having their state of motion or velocity changed when acted on by a force. Mass The quantity of matter in an object. More specifically, mass is the measurement of inertia exhibited by a body. Second Law The acceleration of an object is directly proportional to the net force acting on the object, is in the direction of the net force, and is inversely proportional to the mass of the object.
Force a push of pull that acts to change a body motion or velocity in either direction or magnitude. These can be caused by gravity, electromagnetism, contact with another object, muscles in our bodies, or other possibilities. Weight the gravitational force exerted on an object by the Earth when on the Earths surface. Net force is the sum, vector sum, of all the forces acting on a body. Two opposing forces of equal magnitude will cancel each other out. Forces applied perpendicularly to the velocity will act to change the direction of motion. Drag force from the atmosphere that acts to slow objects down and increases with velocity. Friction force from contact with a surface that acts to slow objects down. Friction does not increase with velocity but it does increase with the contact force (usually weight of the object). Questions and
problems 1. A scientific hypothesis is best described by which of the following: a. A synthesis of a large body of information that encompasses and combines other well-tested and verified ideas b. An idea that has been tested over and over again and has not been contradicted c. An educated guess about the explanation of a phenomenon d. A close agreement by competent observers who make a series of observations about the same phenomena 2. A scientific theory is best described by which of the following: a. A synthesis of a large body of information that encompasses and combines other well-tested and verified ideas b. An idea that has been tested over and over again and has not been contradicted c. An educated guess about the explanation of a phenomenon d. A close agreement by competent observers who make a series of observations about the same phenomena 3. When a weight is tossed straight up in the air, it momentarily comes to a stop at the top of its path. Is it in equilibrium during this brief moment? Why? 4. If you toss a weight straight up in the air, it momentarily comes to a stop at the top of its path. What is its acceleration at the top a. 0 m/s2 b. 10 m/s2 c. Cannot be determined 5. A different staging that weighs 300 N supports two painters, one 250 N and the other 300 N. The reading in the left scale is 400 N. What is the reading in the right hand scale?
6. What is the average speed of a horse that gallops a distance of 15 km in a time of 30 min? Give your answer in km per hour. 7. What is the velocity acquired by a freely falling object 5 s after being dropped from a resting position? 8. What is the acceleration of a vehicle that changes its velocity from 100 km/s to a dead stop in 10 s? 9. Which has more apples a. A one pound bag on the moon b. A one pound bag on the Earth c. A one pound bag of apples is the same size on the moon and Earth |
