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Physics DCA Test Review. What causes an object to accelerate? . An unbalanced force. Match the words below with the words in the box. Balanced: __3__ and __2__ Unbalanced: _1___ and __4__. What does the x axis represent? Time. What does the y axis represent? Distance.
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What causes an object to accelerate? • An unbalanced force
Match the words below with the words in the box • Balanced: __3__ and __2__ • Unbalanced: _1___ and __4__
What does the y axis represent? • Distance
What does the line represent? • Speed
At what letter on the graph is this person traveling at a constant speed? • A, C, D, E – straight, slanted line
At what point is the person traveling back to start? • C – line is negative
At what point is this person going the fastest, and how do you know? • D – Steepest line
Circle the areas on the graph that are balanced forces? • Every letter can be circled – constant speeds and at rest are balanced forces
Put a star on the graph where the person is being effect by unbalanced forces • See above – unbalanced force – change in speed or direction
What is the difference between balanced and unbalanced forces? Balanced – at rest, net force zero, constant speed Unbalanced – net force more than zero, accelerating
Draw a balanced force (using arrows and net forces) on the object below.
Draw an unbalanced force (using arrows and net forces) on the object below.
600 N Down 150 N Right 205 N Right
Fill in the blank • Velocity includes speed and __direction___. Speed only includes ____Distance____ and ______Time____.
What is the equation for speed? Speed = distance ÷ time
Fill in the blank • If you know a car traveled 300 km in 2 hours you can find ___150 km/hour_____.
Formulas • A train traveling 100 km in 4 hours is traveling at what average speed? • 25 km/hour
What is causes the force in the picture below? the string exerts a force on the ball and causes it to move in a circle
If a car with a mass of 25kg and a bus with a mass of 100kg slow to a stop at the same time, which vehicle’s brake will need more force to stop the object? • The bus will need to apply more force to its brakes, because it has more mass
How is a balloon a good example of Newton’s 3rd law (action/reaction)? • Action – air exiting balloon to one side; Reaction – balloon moving the other direction
If a cart with a mass of 50g and a cart with a mass of 70g were give the same push (force), which cart would accelerate faster and why? • The cart with less mass (50kg) will accelerate faster because it has less mass
If the truck is going forward in the direction of the arrow, and suddenly stops. What will happen in the ball inside the truck?
Why does it take a greater force to move a greater mass? Because the more mass an object has, the greater the force needed to move it. F=ma
Newton’s 1st Law An object in motion will stay in motion, an object at rest will stay at rest, unless an outside force is exerted on it
Newton’s 2nd Law • The acceleration of an object depends on the force and mass • More force = more acceleration • More mass = less acceleration
Newton’s 3rd Law For every action there is an equal and opposite reaction