Physical Science Chapter 2
A car goes from 80 km/h west to 20 km/h west in 0.5 h. What is the acceleration in km/h2?
a(vf -vI)/t = (20 km/h - 80 km/h)/0.5 h = -120 km/h2 west.
A cross-country runner runs 10 km in 40 minutes. What is his average speed?
s = d/t = 10 km/40 min = 0.25 km/min
You travel 190 km in 2 h. What is your speed in km/h?
v = d/t = 190 km/2 h = 95 km/h
Displacement includes both distance and direction. A) True B) False
A) True
The relationship s = d/t can be used to calculate speed, distance or time. A) True B) False
A) True
The rate at which an object's velocity changes is called its _____. A) acceleration B) average velocity C) displacement D) scalar magnitude
A) acceleration
The path of a projectile is ____. A) curved B) always horizontal C) always vertical D) straight
A) curved
If you ride your bicycle down a straight road for 500 m then turn around and ride back, your distance is ____ your displacement. A) greater than B) equal to C) less than D) can't determine
A) greater than
A single point on a distance-time graph tells the ____. A) instantaneous speed B) average speed C) constant speed D) average velocity
A) instantaneous speed
The speed you read on a speedometer is ____. A) instantaneous speed B) constant speed C) average speed D) velocity
A) instantaneous speed
To describe velocity you need to know ____. A) speed and direction B) speed and time C) direction and acceleration D) speed and acceleration
A) speed and direction
A merry-go-round horse moves at a constant speed but at a changing ____. A) velocity B) balanced force C) inertia D) unbalanced force
A) velocity
The equation used to find acceleration is a = ____. A) vf - vi /t B) v/t C) vi - vf /t D) vi + vf /t
A) vf - vi /t
On a speed-time graph, a horizontal line shows the change in speed is ____. A) -10 B) 10 C) 1 D) 0
D) 0
Acceleration involves a change in ____. A) time B) direction C) speed D) both b and c
D) both b and c
Speed is the rate of change in ____. A) velocity B) time C) direction D) distance
D) distance
If you ride your bike up a hill, then ride down the other side, your acceleration is ____. A) all positive B) all negative C) first positive, then negative D) first negative, then positive
D) first negative, then positive
Motion is a change in ____. A) time B) speed C) velocity D) position
D) position
The distance traveled divided by the time taken to travel the distance is ____. A) average speed B) mass C) momentum D) speed
D) speed
When you graph the motion of an object, you put ____ on the horizontal axis and ____ on the vertical axis. A) speed, time B) distance, time C) time, speed D) time, distance
D) time, distance
If gravity did NOT affect the path of a horizontally thrown ball, the ball would ____. A) go straight up B) fall straight down C) follow a curved path D) travel horizontally
D) travel horizontally
A horizontal line on a velocity/time graph shows ____ acceleration. A) positive B) negative C) changing D) zero
D) zero
What is the difference between distance and displacement?
Distance is the length of a route traveled. Displacement consists of direction as well as distance.
A truck travels to and from a stone quarry that is located 2.5 km to the east. What is its distance? What is its displacement?
5 km, 0 km
A line on a speed-time graph with a steep slope indicates a greater speed. A) True B) False
A) True
Acceleration occurs when velocity changes. A) True B) False
A) True
As a moving object's velocity decreases, its momentum decreases. A) True B) False
A) True
A car has an acceleration of -5 m/s2. Describe the car's motion.
The car is slowing down at the rate of 5 m/s every second.
A falling leaf has less momentum than a pile of leaves on the ground. A) True B) False
B) False
Acceleration is calculated by dividing change in speed by total time. A) True B) False
B) False
If you are driving up a curvy mountain road, your displacement would be greater than your distance. A) True B) False
B) False
If you travel through a city and find that you travel 5 km in 30 minutes, you could say that your constant speed is 6 km/h. A) True B) False
B) False
If you were trying to get out of the way of a storm, you would need to know the speed at which it was moving. A) True B) False
B) False
Motion is a change in direction. A) True B) False
B) False
The slope of the line on a speed-time graph tells the speed. A) True B) False
B) False
The total distance traveled divided by the constant speed is the average speed. A) True B) False
B) False
To find acceleration, subtract the final velocity from the initial velocity and divide by the time. A) True B) False
B) False
When you push on a sled and it begins to go downhill, you cause negative acceleration. A) True B) False
B) False
When you run around a track at 5 km/h, your velocity is constant. A) True B) False
B) False
In the absence of air, a penny and a feather that are dropped from the same height at the same time will ____. A) fall at different rates B) fall at the same rate C) float D) not have momentum
B) fall at the same rate
A real car moving at 10 km/h has more momentum than a toy car moving at the same speed because the real car ____. A) generates less friction B) has greater mass C) has less mass D) has greater forward motion
B) has greater mass
The unit of momentum is ____. A) kg ´ m B) kg ´ m/s C) kg ´ m/s2 D) m/s2
B) kg ´ m/s
3 m/s north is an example of a(n) ____. A) speed B) velocity C) position D) acceleration
B) velocity
Acceleration is a change in ____. A) speed B) velocity C) displacement D) position
B) velocity
If a drag racer wins the final round of her race by going an average speed of 198.37 miles per hour in 4.537 s, what distance did he cover? A) 157,401 miles B) 2.500 miles C) 0.2500 miles D) 0.0121 miles
C) 0.2500 miles 4.537 s/60 s per min = 0 .07562 min 0 .07562 min/60 min per h = 0.001260 h (198.37 mph)(0.001260 h) = 0.2500 miles
In the equation p = m ´ v, the p represents ____. A) friction B) inertia C) momentum D) position
C) momentum
Acceleration is rate of change of ____. A) position B) time C) velocity D) force
C) velocity
What is the distance traveled by a vehicle in 12 minutes, if its speed is 35 km/h?
Speed is given in km/h, therefore convert time in minutes to hours. distance traveled = (speed)(time taken) = (35 km/h)(12 min)(1 h/60 min) = 7.0 km
Two cars are traveling along the same road at the same speed but at different velocities. Explain.
The two cars are traveling in different directions.
Two cars start at the same point and drive in a straight line for 5 km. At the end of the drive their distances are the same but their displacements are different. Explain.
The two cars drove in different directions.
Describe how both velocity and acceleration are rates of change.
Velocity is the rate of change of position. Acceleration is the rate of change of velocity.
A car is driving down a road. Is it possible for its position to be changing and its acceleration to be zero? Is it possible for its velocity to be changing and its acceleration to be zero?
Yes, it could have constant speed. No, a change in velocity is always an acceleration.
An inline skater is skating around a parking lot. Can she have constant speed and a changing velocity? Changing speed and constant velocity? Explain your answers.
Yes, the skater could be changing directions. No, any change in speed will change the velocity.