Definitions
Define speed
How fast something is moving from point A to point B.
Rubbing my hands together causes a force called _____________. (Bonus 100 points if you can identify which type it is).
Friction; sliding friction
The formula for calculating speed is ___________
Speed = Distance / Time
5 inches/minute; 0 inches/minute
Craig and Pete are pushing on a box in the same direction at 5N and 10N respectively. The net force is this:
15N
Speed + direction
When trying to walk outside during a hurricane against the wind, you experience this kind of friction.
Fluid friction
It took Sally 3 seconds to walk 3 meters. Her speed is this (No points if you get the units wrong!)
1 m/s
The formula for calculating acceleration is _____________
Acceleration = (Final Velocity - Initial Velocity) / Time
Beyonce is pushing a box to the left with 20N of force, but there is static friction pushing in the opposite direction at 8N. The net force and direction of the box is this:
12N moving to the left
Define force
Something that causes an object to change its speed or direction
True or False: When I am pushing a box, the friction between the floor and the box trying to prevent the box from moving is called static friction.
True
It took Bill 1.5 hours to drive 50 miles. What was his average speed? (No points if you get the unit wrong)
about 33.3 miles/hour
Bob was driving his car at 2,700 miles/minute before speeding up to 3,900 miles/minute when he finally reached the expressway. It took him 3 minutes to reach that speed. This is his acceleration: (no points if you do not get the units correct!)
400 miles/minutes2
The net force of this box is:
________________
10 N ---------> | | <------------- 5 N
5 N -----------> |_ _ _ _ _ _ _ _ | < -------------- 10 N
0 N
Define motion
When a force is applied that causes an object to change its position
The friction going against gravity is called this. (Bonus 100 points if you can identify which type of friction it is)
Air Resistance, fluid friction
Sally is trying to outrun the cops. She was driving at an average speed of 80 miles/hr down the highway, but the chase ended 3 hours later. Her distance was this number:
240 miles
You are traveling in a car that is moving at a velocity of 20 m/s. Suddenly, a car 10 meters in front of you slams on it’s brakes. At that moment, you also slam on your brakes and slow to 5 m/s. Calculate the acceleration if it took 2 seconds to slow your car down.
-7.5 m/s2
True or False: the following is an example of balanced forces.
A few kids are playing tug of war. Jenny is pulling on a rope at 15N, while Cornell and Daria are working together to beat Jenny. Their forces are 7N and 6N respectively.
False
Define acceleration
The rate of change of speed from one point in time to another
Someone is skateboarding before their front wheels hit a rock, causing them to fall and slide down a grassy hill. List all the friction forces working against them.
Fluid --> the air pushing against them while skateboarding
Rolling --> the wheels turning on the pavement
Static ---> the rock abruptly applies static friction to put the skateboard at rest
Sliding --> the person slides down against the hill's grass
Mike's speed is 100 km/hour and he drove 350 km. Assuming he did not slow down or stop at any point, he drove for this much time:
3.5 hours
If a Ferrari, with an initial velocity of 10 m/s, accelerates at a rate of 50 m/s2 for 3 seconds, what will its final velocity be?
160 m/s2
Draw on the board an example of an object having a net force of 15N moving up and 13 N to the left. There should be arrows pushing on the object in all four directions.
Varies