Physics 201/211

The spaceship will begin to slow down Physics 201/211 Warm-up Question A spaceship has a force, F1, acting on it in the +x direction. It also has two other forces, F2 and F3 acting 120o up and 120o down from the +x direction, respectively. If the spaceship is traveling at a constant speed in the +x direction and the magnitude of all the forces is the same, which statement is true? The spaceship will begin to slow down The spaceship will begin to accelerate downward The spaceship will begin to speed up in the positive y direction The spaceship will begin to speed up in the positive x direction None of the above 2

What must the mass of m3 be to slide m2 out from under m1? Physics 201/211 What must the mass of m3 be to slide m2 out from under m1? m1=1kg m2=3kg m3

To go to a football stadium from your house, you first drive 1000m north, then 500m west, and finally 1500m in a direction 20o south of west. (a) relative to your home, the football stadium is in what direction? How far away is your house from the stadium in a straight line?  

Walking along the beach you notice there is an island at an angle of 30o with respect to the shore. You then walk 50m along the shore, ending on the other side of the island. A measure tells you the island is now 40o out from the shore. How far away is the island from the shore?  

Physics 201/211 70 60 Static Equilibrium A 1000 kg steel beam is supported by two cables. What is the tension in each cable? 60 70 6

Physics 201/211 A 90 kg man is standing on a scale that determines weight. This scale is in an elevator that is accelerating in the upward direction. Will the man’s 90 kg: A. increase B. decrease C. stay the same 7

Physics 201 Quiz Question A gerbil runs 85cm in a straight line. This takes it 5s. Then the gerbil turns around and runs in the opposite direction 65cm. This takes it 3s. What is the magnitude of the gerbil’s average velocity for the entire trip? 21.7cm/s 17.0cm/s 19.3cm/s 0.25cm/s 0.667cm/s 20.0cm/s

Are two vectors with the same magnitude necessarily equal?

Physics 201 Discussion Question What is the total distance Δx traveled by the particle? 50m 40m 30m 20m

Physics 201

A father is now three times as old as his son A father is now three times as old as his son. Twelve years ago he was six times as old as his son. Find the present age of each.  

Physics 201/211 It takes 0.2 second for the back end of a 1500kg car to crumble within 2m of the front end, in a collision with an immovable concrete wall. What is the net force that acts on the front bumper during this time?   13

Physics 201 Quiz Question Which plot represents the velocity vs. time of the particle represented by the position vs. time graph?

Physics 201 Discussion Question Below a plot of the position vs. time has been drawn. Draw the corresponding acceleration and velocity graphs.

Physics 201 Discussion Question Below a plot of the position vs. time has been drawn. Draw the corresponding acceleration and velocity graphs.

Physics 201 Quiz Question Use dimensional analysis to determine what the area under the curve represent? Average Velocity Speed Acceleration Distance traveled

Physics 201 Discussion Question Below a plot of the velocity vs. time has been drawn. Draw the corresponding acceleration and position graphs.

Physics 201 Discussion Question Below a plot of the position vs. time has been drawn. Draw the corresponding acceleration and velocity graphs.

Physics 201 Quiz Question

Physics 201

Physics 201 Describe what’s happening What is Fred’s average speed? What is Brutus’s average speed?

Physics 201/211

Physics 201/211 Describe what’s happening

Physics 201/211 A 90 kg man is standing on a scale that determines weight. This scale is in an elevator that is accelerating in the upward direction. Will the man’s apparent weight: A. increase B. decrease C. stay the same 25

Physics 201/211 a.) How much force does an 80 kg astronaut exert on his chair while sitting at rest on the launch pad? b.) How much force does an 80 kg astronaut exert on his chair while accelerating straight up at 10 m/s^2? 26

Physics 201/211 No Friction A 10 kg crate is being slid across a frictionless floor by a 40 N force acting at an angle of 35 degrees below the horizontal. How far will the crate slide after 10 seconds? 27

Physics 201/211 Friction a.) A 10 kg crate is being pushed on by a 40 N force acting at an angle of 35 degrees below the horizontal. What coefficient of static friction will keep this crate from moving? b.) If the coefficient of kinetic friction is 10% less than that of static friction, what will the acceleration of the crate be? 28

The daughters acceleration is the same as here fathers Physics 201/211 Discussion Question Standing on ice, a father and daughter face each other, pressing flat hands together. They push off each other and start moving away from each other. Which of these statements is correct. The daughters acceleration is the same as here fathers Both are decelerating since their push is in the opposite direction of their motion While in contact their hands are not moving After they push off, both leave with the same speed None of the above 29

Physics 201/211

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Physics 201 Discussion Question What is average velocity of the particle over the time interval Δt=50.0s? 30m/s 0.6m/s 2.0m/s 10m/s

Physics 201/211 Find the tension in each cable and the applied force F required for that the system to not move. 33

Physics 201/211

Physics 201 Discussion Question Below a plot of the position vs. time has been drawn. Draw the corresponding acceleration and velocity graphs.

What must the mass of m3 be to slide m2 out from under m1? Physics 201/211 What must the mass of m3 be to slide m2 out from under m1? m1=1kg m2=3kg m3 36

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