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Chapter N4. Motion from forces Due Friday: N4.B1, B2, B.7, B.8. These are graphs showing the motion of a car along a straight road. Explain what is happening to the displacement, the velocity and the acceleration of the car. r. v. a. t. Problems.
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Chapter N4 Motion from forces Due Friday: N4.B1, B2, B.7, B.8
These are graphs showing the motion of a car along a straight road. Explain what is happening to the displacement, the velocity and the acceleration of the car. r v a t
Problems • Case 1. An object is thrown straight into the air and falls back. t=0 when the object leaves the hand which happens at y = 0. Draw the curve until the object comes back to the starting point. • Case 2. A rocket is shot straight in the air with an engine that burns for 4 seconds. It then falls back to earth.
Equations for your formula sheet Similar equations exist for y, and z. Use the x, y, or z equations depending on the direction of the force (acceleration). Often this will be the vertical direction and the acceleration will be g.
Sample problem: A car starts from rest and accelerates (2m/s2)for 5 seconds. What are the velocity and position of the car at that time? • List the data on your paper, raise your hand when you are done. 6 • x0=0, v0=0, a=2 m/s2, t = 5 sec, v = ?, x = ?. v=10m/s x=25m
An object is dropped starting from rest from a height of 25 m. Find the position and velocity of the object at the end of 2.2 s. • Write the data. Raise your hand when done. • y0=25 m, v0=0, a = -9.8 m/s2, t = 2.2 s, v = ?, y = ? v = - 9.6 m/s y = 23.7 m How long will it take the ball to strike the ground? t = 2.26 s
An object thrown straight up from a height of 25 m with a velocity of 12 m/s. Find the position and velocity of the object at the end of 2.2 s. • Write the data. Raise your hand when done. • y0=25 m, v0=12 m/s, a = -9.8 m/s2, t = 2.2 s, y = ?, vy=? v = - 9.6 m/s m/s y = -23.7 + 26.4 + 25 m = 27.7 m t = 3.8 s
A ball is thrown straight into the air and takes 3 seconds to fall back to the ground. • What is the maximum height of the ball and with what velocity was it thrown into the air? • Write the data. • Write the equation to find the velocity with which it was thrown. • Find the velocity. • Write the equation to find the height. • Find the height. v = 14.7 m/s y = 11 m
Problems due Friday • N4.B1, B2, B.7, B.8