Unit 2 - 2D Kinematics

vector

a physical quantity with both magnitude and direction

resultant

the sum of two or more vectors

resolving a vector into components

replacing a vector with scalers

projectile motion

the motion of an object projected in a gravitational field, such as from Earth’s surface, and moving along a curved path

when an object starts freefall, how does the horizontal axis change?

it doesn’t

if one object is dropped horizontally and the other vertically from the same height, what time will each object land?

they will both land at the same time because they have the same vertical velocity

vertical velocity

velocity along the y-axis

horizontal velocity

velocity along the x-axis

what is the shape of a parabolic motion?

completely symmetrical half circle

v_ix

v_icos(-)

v_iy

v_isin(-)

if two objects are thrown, one horizontally and one vertically, which object has the higher final velocity and why?

the one thrown horizontally because it has the combined velocity of the y axis and the x axis

An object is dropped from a plane flying at a constant speed. When the object hits the ground where is the plane in terms of the object?

directly over the package

For general projectile motion, does the horizontal component of a projectile’s velocity increase, decrease, stay constant, or stay at zero?

it stays constant

at the highest point of the trajectory of a soccer ball, is the acceleration or velocity at zero?

both are not zero

what is true about an object's horizontal and vertical accelerations in 2D projectile motion?

the horizontal acceleration is always zero and the vertical acceleration is always a negative constant

if two objects are thrown at the same angle but one is thrown upwards and one is thrown downwards, what is true about the objects as they are about to hit the ground?

both objects will have the same speed and the one thrown downwards will reach the ground before the one thrown upwards

Rocks are thrown off the same building, one vertically and one at 30 degrees with twice the speed of the vertical one. Which rock hits the ground first?

they hit the ground at the same time