20 m/s
A player kicks a football straight up into the air. The ball takes 2.0 s to reach its highest point. Approximately how fast was the ball moving when it left the player’s foot?
magnitude
The ______ of a vector is always a positive quantity.
right, up
Ax is positive if Ax is directed _______; Ay is positive if Ay is directed _______.
angle of the ramp
The acceleration of a cart rolling down a ramp depends on
is directed down at all times
The acceleration vector of a particle in projectile motion
points towards the center of the circle
a=v²/r
a=v²/r
The acceleration vector of a particle in uniform circular motion
tangent to the path
The velocity vector of circular motion is
magnitude
Ax is the __________ of the vector Ax
5m/s
pythagorean theorem 3-4-5 triangle!
A factory conveyor belt rolls at 3 m/s. A mouse sees a piece of cheese directly across the belt and heads straight for the cheese at 4 m/s. What is the mouse’s speed relative to the factory floor?
they hit the ground at the same time
A heavy red ball is released from rest 2.0 m above a flat, horizontal surface. At exactly the same instant, a yellow ball with the same mass is fired horizontally at 3.0 m/s. Which ball hits the ground first?
2.0m
A 100-g ball rolls off a table and lands 2.0 m from the base of the table. A 200-g ball rolls off the same table with the same speed. It lands at distance
yes
A car is traveling around a curve at a steady 45 mph. Is the car accelerating?
4
A toy car moves around a circular track at constant speed. It suddenly doubles its speed — a change of a factor of 2. As a result, the centripetal acceleration changes by a factor of
point in the direction of displacement
Velocity vectors
Ay= Asinθ
Ax= Acosθ
θ= tan-1 (Ay/Ax)
magnitude of A= √(Ax²+ Ay²)
signs depend on direction of vector
Ax= Acosθ
θ= tan-1 (Ay/Ax)
magnitude of A= √(Ax²+ Ay²)
signs depend on direction of vector
Vector components
object acceleration and velocity are parallel to the surface
signs depend on tilt direction
ax=± gsinθ
signs depend on tilt direction
ax=± gsinθ
Motion on ramp
(vx)O2-O1=(vx)O2-surface + (vx)O1-surface
Relative Motion speed of object 2 with respect to object 1
path is a parabola
object moves through 2 dimesnion under influence of gravity and nothing else
vertical motion with free fall acceleration ay=-g and (vy)i= vi sinθ
horizontal motion with constant velocity (vx)i= vi cosθ
object moves through 2 dimesnion under influence of gravity and nothing else
vertical motion with free fall acceleration ay=-g and (vy)i= vi sinθ
horizontal motion with constant velocity (vx)i= vi cosθ
Projectile motion
