1) Why is it that an object can accelerate while traveling at a

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1) Why is it that an object can accelerate while traveling at a Powered By Docstoc
					Why is it that an object can accelerate while traveling at a constant speed, but not at a constant velocity? Suppose you roll a bowling ball into a pillow and the ball stops. Now suppose you roll it against a spring and it bounces back in the opposite direction with the same speed. Which object causes a greater impulse, the pillow or the spring? EXPLAIN. Would it be a good idea to jump from a very small rowboat to a dock that seems within jumping distance? EXPLAIN. A massive ball is suspended on a string and pulled by another string as shown below. Which string will break and WHY?

String being pulled.

You are stranded on frozen pond and there is little friction between you and the surface. You shout to your friend for some assistance and he slides you a heavy stone that comes to rest at the base of you feet. How can you use this stone to get to safety? What are the principle(s) behind your answer? Supposing a snowmobile is equipped with a flare launcher which is capable of launching a flare vertically (relative to the snowmobile). If the snowmobile is in motion and launches the flare and maintains a constant horizontal velocity after the launch, then where will the flare land (neglect air resistance)? EXPLAIN. Two objects of are traveling with the same initial velocity across a smooth surface. Object A has a mass m and object B has a mass 5m. Object A has twice the surface area of object B. They are both made of the same material and have the same coefficient of kinetic friction. Which object will slide farther before coming to a stop? EXPLAIN using FBD’s, words, and mathematical representations. All of the sudden, our sun becomes a black hole. This means that its mass will stay the same, but its radius will become very very small. What will happen to our solar system? EXPLAIN. A pitcher throws a pitch perfectly horizontal, but it unfortunately hits the batter. Where should the batter stand to minimize the pain of getting hit by a pitch? EXPLAIN. (THE BATTER WILL BE HIT BE THE PITCH NO MATTER WHAT! IT IS ALSO NOT A QUESTION OF WHERE ON THE BODY YOU FEEL THE LEAST PAIN!!!) During the year, we smashed a cinderblock with a sledgehammer while lying on a bed of nails. Explain why Mr. G was NOT hurt during the demonstration. Surprisingly we can use only a tape measure to find the speed of a potato coming out of a potato gun. Explain how we can do this. Assume the potato will be shot perfectly horizontal.

You are standing on a scale in an elevator that is initially at rest. Explain what will happen to the reading on the scale when the elevator starts to move up, when it is traveling at a constant velocity, and when it slows down at the top. Draw FBD’s to help represent your explanation. While making a left turn in your car, you feel like you body is being pushed to the right. EXPLAIN. Why are cars with anti-lock brakes safer than cars without? A projectile is thrown straight up. What are two ways you can find the initial velocity of the projectile? Why were we unable to break an egg while throwing it as hard as we could into a sheet while at the same time the egg broke if we just dropped it on the ground? While traveling on a rollercoaster, you feel lighter while going over the top of a hill and heavier while traveling at the bottom of a hill. Use FBD’s and words to explain why this is true. To the right is a FBD of an unknown object. Describe all the possible types of motion for the object.

Two projectiles are shot with the same initial velocity and from the same height. They both land at the same height they were fired at. Explain how it is possible to fire to projectiles and have them travel the same horizontal distance if they are fired at two different angles. Two people are holding a rope between them. One person has a mass m and the other has a mass 2m. Describe the motion of each person if the more massive person pulls on the rope. Be sure to use words like “three times” as much. Please use words and math to explain your answer. A 100 kg person walks up a 15 m long incline and ends up 5 m above the ground. A 50 kg person walks up a 30 m long incline and ends up 10 m above the ground. The first person takes half as much time as the second person. Please explain who does more work. Also decide which person uses more power. A compact car and an 18-wheeler both starting from rest accelerate at the same rate to a final velocity. Answer the following questions: Which vehicle’s engine did more work? EXPLAIN Which vehicle has a greater kinetic energy? EXPLAIN Is it possible for them to have the same kinetic energy? EXPLAIN How can you use a spring powered dart gun to find the spring constant of the spring that launches the dart?

REMOVED FROM 08 QUESTIONS TO MAKE ROOM FOR ENERGY If an elephant were chasing you, its enormous mass would be very threatening. However, if you zigzagged, the elephant’s mass would be to your advantage. Why? Your friend says that rockets are unable to accelerate in space because there is no air for the rocket to push off of. Is your friend right or wrong? EXPLAIN How can you use a record player to find the coefficient of friction between two objects? A long jumper wants to maximize his/her jumping distance. Is the distance dependent on the vertical component of velocity, horizontal component of velocity, or a combination of both? EXPLAIN.

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