Read the graph
On a speed vs. time graph, what does a flat horizontal line mean?
Constant speed: forces are balanced, no net force
What is a force?
A push or a pull
The stick pushes the same puck harder. Is the acceleration bigger or smaller?
Bigger
A puck slides 30 m in 2 s. What is its speed?
15 m/s
A puck speeds up from 0 to 20 m/s in 0.5 s. What is its acceleration?
40 m/s²
What does a line sloping upward on a speed vs. time graph mean?
The object is speeding up
What unit do we measure force in?
Newtons (N)
A puck has twice the mass and gets the same force. What happens to its acceleration?
It is cut in half
A driver going 20 m/s has a reaction time of 0.5 s. What is the reaction distance?
10 m
A 2 kg cart accelerates at 3 m/s². What is the net force on it?
6 N
What does the slope of a speed vs. time graph tell you?
The acceleration
What do we call the force that slows a car down when the driver presses the brakes?
Braking force
The braking force doubles. What happens to the stopping time?
It is cut in half
A texting driver going 20 m/s has a reaction time of 1.5 s. What is the reaction distance?
30 m
A 10 N force pushes a 0.5 kg puck. What is its acceleration?
20 m/s²
A line goes from 10 m/s down to 0 m/s. Is the acceleration positive or negative?
Negative, because the object is slowing down
Which has more friction: ice or a rubber floor?
A rubber floor
A car goes twice as fast with the same mass and brakes. What happens to its stopping time?
It doubles
A car going 10 m/s takes 3 s to brake to a stop. What is its braking distance?
30 m (10 × 3)
A 1,000 kg car moving at 20 m/s brakes with 5,000 N. What is its stopping time?
4 s
On a distance vs. time graph, what does a steeper line mean?
The object is moving faster
Two pucks slide at the same speed, one on ice and one on a rubber floor. Which one stops first, and why?
The one on the rubber floor, because more friction slows it down faster
A car has 2× the mass, 3× the speed, and 6× the braking force. How does its stopping time compare to the original?
It is the same (2 × 3 ÷ 6 = 1)
A car going 15 m/s has a 1 s reaction time and a 2 s braking time. What is the total stopping distance?
45 m (15 m reaction + 30 m braking)
A 1,500 kg car slows from 20 m/s to 0 in 5 s. What is its braking force?
6,000 N (a = 4 m/s², F = 1,500 × 4)