Physics 2065A/B Study Guide - Midterm Guide: Rolling Resistance, Elastomer, Inelastic Collision

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rosegnu47

31 Jan 2013

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Velocity is vector, speed is scalar; vectors have direction!!! Use vector diagrams to identify forces; free body diagrams. Average speed, change in displacement over time, measured m/s or km/h. Average acceleration, change in average speed over time, measured m/s . N2 (law of acceleration/force/motion): net force on object is equal to the product of the mass and acceleration of the body (ma is fnet); empirical formula relating acceleration and force. Gravity as a force: downward force that pulls an object toward the centre of the earth due its mass; n2: Fy= mg where g is 9. 8m/s (acceleration due to gravity; magnitude of this force is called weight) Kinetic friction: once body starts moving; static friction becomes kinetic friction (fk) Galileo"s hypothesis regarding drag force and terminal velocity: all objects fall with the same velocity in the absence of air resistance.

Related Questions

Galileo thought about whether acceleration should be defined as the rate of change of velocity over time or as the rate of change in velocity over distance. He chose the former, so let’s use the name “vroomosity” for the rate of change of velocity over distance. For the motion of a particle on a straight line with constant acceleration, the equation v = v_i + at gives its velocity v as a function of time. Similarly, for a particle’s linear motion with constant vroomosity k, the equation v = v_i + kx gives the velocity as a function of the position x if the particle’s speed is v_i at x = 0. (a) Find the law describing the total force acting on this object of mass m. Describe an example of such a motion or explain why it is unrealistic for (b) the possibility of k positive and (c) the possibility of k negative.

violethorse873

Part A

An object cannot remain at rest unless which of the following holds?

The net force acting on it is zero.

The net force acting on it is constant and nonzero.

There are no forces at all acting on it.

There is only one force acting on it.

Part B

If a block is moving to the left at a constant velocity, what can conclude?

There is exactly one force applied to the block.

The net force applied to the block is directed to the left.

The net force applied to the block is zero.

There must be no forces at all applied to the block.

Part C

A block of mass 2kg is acted upon by two forces: 3N (directed to the left) and 4N (directed to the right). What can you say about the block's motion?

It must be moving to the left.

It must be moving to the right.

It must be at rest.

It could be moving to the left, moving to the right, or be instantaneously at rest.

Part D

A massive block is being pulled along a horizontal frictionless surface by a constant horizontal force. The block must be __________.

continuously changing direction

moving at a constant velocity

moving with a constant nonzero acceleration

moving with continuously increasing acceleration

amethystraven1

When a 0.058 kg tennis ball is served, it accelerates from rest to a speed of 45.0 m/s. The impact with the racket gives the ball a constant acceleration over a distance of 0.440 m. What is the magnitude of the net force acting on the ball?

What is the average velocity of the ball?
Over what time period was the ball struck?
What is the acceleration of the ball?
What is the net force on the ball?
If the ball had been heavier, but experienced the same change in velocity, would the applied force have to be greater or lesser than before?

bronzealpaca798

Physics 2065A/B Study Guide - Midterm Guide: Rolling Resistance, Elastomer, Inelastic Collision

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