Linear Motion
Consider drops of water leaking from a water faucet. As the drops fall they
get further apart
When you look at a speedometer in a moving car, you can see the car's
instantaneous speed
When a basketball player jumps to make a shot, once his feet are off the floor, the jumpers acceleration
is g; no more, no less
If you drop a feather and a coin at the same time in a vacuum tube, which will reach the bottom of the tube first?
neither they will both reach the bottom at the same time
A ball is thrown upwards and caught when it comes back down. In the absence of air resistance, the seed of the ball when caught would be
the same speed it had when thrown upwards
True or False: Even though a car is slowing down, it is still accelerating (in the most general form of acceleration)
true
True or False: The rate at which a distance is covered is called speed
true
True or False: Velocity is different from speed because it is in a given direction
true
True or False: motion is described relative to something else
true
True or False: the rate at which velocity changes with time is called acceleration
true
a pencil lies on your desk. if the earth is moving around the sun at a speed of 30km/s, how fast is the pencil moving relative to... the desk?...the sun?
0km/s; 30km/s
A train travels 6 meters in the first second of travel, 6 meters again during the second second of travel, and 6 meters again during the third second. It's acceleration is?
0m/s squared
Suppose a jumper claims a hang time of two seconds. Then that jumper must jump a vertical distance of
5m
a car starts from rest and after 7 seconds it is moving at 42 m/s. What is the car's average acceleration?
6m/s squared
If a ball were equipped with a speedometer and allowed to fall freely on a planet where the acceleration due to gravity is 23m/s squared, the reading on the speedometer would increase each second by
23m/s
suppose a car is moving in a straight line and steadily increases it's speed. It moves from 35km/h to 40km/h the first second and from 40km/h to 45km/h the next second. What is the car's acceleration
5km/h
A car accelerates at 2m/s squared. Assuming the car starts from rest, how much time does it need to accelerate to a speed of 20m/s squared.
10 seconds
If a projectile is fired straight up at a speed of 30m/s, the total time to return to its starting point is
6 seconds
suppose you take a trip that covers 180km and takes 3 hours to make. Your average speed is
60km/h
A freely falling object starts from rest. After falling 6 seconds, it will have a speed of about
60m/s
If you drop a feather and a coin at the same time in a tube filled with air, which will reach the bottom of the tube first?
The coin
Acceleration
The rate at which velocity itself changes
suppose you are in a car that is going around a curve. The speedometer reads a constant 30mph. Which of the following is NOT true?
Your velocity is constant
suppose an object is in free fall. Each second the object falls
a larger distance than in the second before
If a freely falling object were somehow equipped with a speedometer, its speed reading would increase each second by
about 10m/s
A ball is thrown straight up. At the top of it's path the acceleration is
about 10m/s squared
When something falls to the ground it accelerates. This acceleration is called the acceleration due to gravity and is symbolized by the letter g. What is the value of g on Earth's surface?
about 10m/s squared
In the absence of air resistance, objects fall at a constant
acceleration
A ball tossed vertically upward rises, reaches it's highest point, and then falls back to it's starting point. During this time the acceleration of the ball is always
directed downward
True or False: A unit of velocity is the meter
false
True or False: Average speed is defined as the time it takes for a trip divided by the distance
false
True or False: a ball is thrown into the air at the highest point it has zero velocity and zero acceleration
false
True or False: as a ball falls freely the distance it falls each second is the same
false
True or False: when a car rounds a corner at constant speed, its acceleration is zero
false
True or False: when we discuss the speed of things we mean with respect to the center of the universe
false
True or False: a unit of acceleration is m/s
false: m/s squared
Acceleration is defined as the change in
velocity divided by the time interval
As an object freely falls in a vacuum, its...
velocity increases
