PH 144 Pre Health Physics I SUSPENDED WATER

PH 144 Pre Health Physics I

SUSPENDED WATER http: //www. youtube. com/watch? v=7 cta. A 2 m. ERz. I CELLPHONE POPCORN http: //www. youtube. com/watch? v=V 94 shlq. Pl. SI

Constant Velocity • Draw a set of axes, labelled Distance (m) along the vertical, and Time (s) along the horizontal • Draw a line for each of the following scenarios: – An object starting at 0 m with a constant forward velocity. (Remember: Velocity = Increase in displacement over time) – An object starting at 0 m with a constant forward velocity, which then comes to a stop. – An object which moves with constant forward velocity, then reverses direction and returns to the original location.

Signs of Velocity and Acceleration • If the velocity and acceleration are in the same direction (both have the same sign, both positive or both negative) the object is speeding up • If the velocity and acceleration are in opposite directions (they have opposite signs), the object is slowing down

Signs of Velocity and Acceleration

Constant Acceleration • Acceleration can change over time but for simplicity sake the average acceleration will be equal to the constant value • The equation relating velocity, acceleration and time is:

Constant Acceleration • Ex. Marley is travelling passenger seat in the car travelling at 90 km/h and wants you to speed up to 140 km/h so he can check out the squirrel he sees in front of him. So you do and that takes 4 seconds. What is your acceleration?

Constant Acceleration • Ex. Marley is travelling passenger seat in the car travelling at 90 km/h and wants you to speed up to 140 km/h so he can check out the squirrel he sees in front of him. So you do and that takes 4 seconds. What is your acceleration?

Constant Acceleration • Ex. Once you reach 140 km/h, Marley now wants you to stop the car after seeing the squirrel because he decides he wants to chase it. If you slow down at 4 m/s 2, how long does it take to come to a stop?

Constant Acceleration • Ex. Once you reach 140 km/h, Marley now wants you to stop the car after seeing the squirrel because he decides he wants to chase it. If you slow down at 4 m/s 2, how long does it take to come to a stop?

Constant Acceleration • Ex. From the previous example, if only the deceleration (4 m/s 2) and speed top speed before slowing (140 km/h) down are given, how much distance is needed to come to a stop?

Questions to Master • Pg. 60: 1, 3, 5, 7, 9, 11, 13, 15