Physics Midterm Study Flashcards
(98 cards)
What is the definition of speed?
Speed is how fast an object is moving (the distance traveled every second).
How does speed differ from velocity?
Velocity requires a direction while speed does not; average velocity is calculated with displacement rather than with distance.
If a person runs with a constant speed of 4 m/s for 20 seconds, how far will they move?
d = st = 4 m/s * 20 s = 80 m
If a person runs with a constant speed of 5 m/s, how long will it take to move 1200 m?
t = ds = 1200 m / 5 m/s = 240 s
What is the definition of acceleration?
The rate at which the velocity of an object is changing.
If a motorcycle accelerates from rest with a rate of 7 m/s², what will its speed be after 3 seconds?
vf = vi + at = 0 + 7(3) = 21 m/s
If a motorcycle travelling at 45 m/s ‘forward’ suddenly accelerates ‘backward’ at 5 m/s², how long will it take to stop?
t = (vf - vi) / a = (0 - 45) / -5 = 9 s
What does the slope of a position vs time graph represent?
The slope of a position vs. time graph represents the object’s velocity.
What does the slope of a velocity vs time graph represent?
The slope of a velocity vs. time graph represents the object’s acceleration.
What is true about the acceleration rate of objects of different mass in freefall, ignoring air resistance?
All masses accelerate at the same rate.
How long does it take for an object to free fall (from rest) from a height of 50 meters?
t = √(2x/a) = √(2(50)/10) = 3.16 sec
If an object free falls (from rest) for 6 seconds, how far has it fallen?
x = vit + (1/2)at² = (1/2)(10)(6²) = 180 m
When an object is tossed straight upward, what is its velocity and acceleration at the peak of its motion?
Velocity at peak is zero; acceleration rate at peak is 10 m/s² downward.
What is inertia?
Inertia is the resistance an object has to changes in motion.
What is the quantity we use to measure inertia?
Mass.
What is a ‘force’?
A force is simply a push or pull on an object.
What is a ‘net force’?
Net force is the sum of all forces acting on an object (with directions taken into account).
State Newton’s 1st Law.
An object will remain in constant motion in the absence of a nonzero net force acting on it.
What does it mean for an object to be ‘in equilibrium’?
Equilibrium is the state of balanced forces, where the net force is zero.
What are the two states of motion possible for an object in equilibrium?
- At rest * Moving with constant velocity
State Newton’s 2nd Law in words.
The acceleration of an object is directly proportional to the net force acting upon it and inversely proportional to its mass.
State Newton’s 2nd Law as an equation.
a = F/m
What does it mean for two variables to be ‘directly proportional’?
If one variable increases, the other variable increases proportionally.
What does it mean for two variables to be ‘inversely proportional’?
If one variable increases, the other variable decreases proportionally.