Speed Calculations
The speed of an object that travels 20 meters in 5 seconds.
What is 4 m/s?
On a distance-time graph, what does a flat line mean?
The object is stopped/not moving = NO MOTION
What is the difference between speed and velocity?
Speed describes how fast an object moves; velocity describes speed AND direction.
What happens when forces are balanced?
There is no change in motion.
What does Newton's First Law say about an object at rest?
An object at rest will remain at rest unless acted upon by an unbalanced force.
A runner travels 14 km in 2 hours. What is the average speed?
7 km/hr
What does a steeper line on a distance-time graph tell you?
Which includes direction: speed or velocity?
Velocity
What is an unbalanced force?
A force that causes a change in an object's motion.
What happens to an object moving at constant velocity when no unbalanced force acts on it?
It will continue moving at the same velocity.
A toy travels 30 cm in 5 seconds. Calculate its average speed.
6 cm/s
How can you tell from a distance-time graph that an object is speeding up?
The line becomes steeper as time increases, curved line showing acceleration.
A car travels 60 mph east. Is this describing speed or velocity? Explain.
Velocity, because it gives both speed (60 mph) and direction (east).
Give an example of balanced forces acting on an object.
A person standing still on the floor OR a box moving at a steady speed on a smooth floor.
A ball rolls across the floor and eventually stops. What caused its motion to change?
An unbalanced force, such as friction, acted on the ball.
A car travels 100 m in 4 s. What is its average speed?
25 m/s
A graph shows distance increasing quickly, then becoming flat. Describe the object's motion.
The object moves quickly and then stops.
Two cars are both traveling 15 m/s, but one is turning. Which car has changing velocity and why?
The car that is turning, because a change in direction means a change in velocity.
Explain how an unbalanced force can cause an object to speed up or slow down.
An unbalanced force changes an object's motion, causing it to accelerate or decelerate.
Use Newton's First Law to explain why a rolling ball eventually stops.
The ball would continue moving if no unbalanced force acted on it, but friction creates an unbalanced force that slows the ball down until it stops.
A toy travels 26 cm in 4 s in trial 1, 13 cm in 2 s in trial 2, then 19.5 cm in 3 s in trial 3. What is the average speed across the trials?
6.5 cm/s
A distance-time graph has three sections: increasing, flat, then decreasing. Explain what is happening during each section.
An object travels at a constant speed but changes direction. Does its velocity change? Explain why.
Yes. Velocity changes because velocity includes direction, even if the speed stays the same.
A ball is moving forward while an unbalanced force acts backward. Predict what happens to the ball's motion.
The ball will slow down/decelerate because the net force is opposite its direction of motion.
Explain how Newton's First Law, balanced/unbalanced forces, and friction work together when a ball rolls across a basketball court.
The ball is initially moving. Friction acts opposite the ball's motion, creating an unbalanced force. This causes the ball to slow down and eventually stop. Without an unbalanced force, the ball would continue moving at the same velocity.