Force and Motion - Robert Purcell | Biblioteka

Instrukcije

This will need to be checked as practice for the assessment on Thursday.

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A student made a ramp by placing one end of a piece of wood on top of three textbooks. He rolled a toy truck down the ramp three times, measured the speed, and recorded the results in a data table. The teacher asked the student to increase the kinetic energy of the truck. Which of these should the student do to meet the criteria?

He should perform additional trials.

He should decrease the height of the ramp.

He should add mass to the back of the truck.

He should change the material of the ramp to increase the friction.

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A team of engineers is developing a new waterslide for a theme park. The riders of the slide will climb several flights of steps to reach the top of the slide and will sit in a round inner tube as they slide down. The engineers are testing a computer simulation to measure the kinetic energy that the riders will have on the slide. The kinetic energy will be based on the potential, or stored, energy and will depend on mass and speed. The engineers want to develop a way to transfer the most kinetic energy to the riders to make their trip down the slide as fast as possible.

Adding twists and turns to the slide

Decreasing the amount of water pushing the riders

Increasing the friction between the tube and the slide

Increasing the height of the slide

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Which puck(s) experienced the strongest force when hit (the green puck has less mass than the black and purple which have equal mass)? How do you know? (All three changed velocity by the same amount)

All three hockey pucks experienced the same force because they changed speed by the same amount.

The black hockey puck; it is more massive and has the fastest ending speed.

The purple hockey puck; it takes a stronger force to slow down a more massive object than to speed it up.

The black and purple hockey pucks; they have more mass than the green puck, but changed speed by the same amount.

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A student makes a balloon cart to investigate how combined forces create motion. The student creates a simple cart by attaching wheels to a small piece of cardboard. The student attaches a straw with a balloon on one end so that any air coming out of the balloon flows in one direction. The student blows up the balloon, sets the cart on the tabletop, and lets go. Air flows out of the balloon and through the straw, but the cart does not move. Which of these explains why the car does not move?

The force of gravity exceeds the other forces acting on the cart.

The forces pushing the cart forward were greater than the force of mass and gravity.

The force on the cart from the air in the balloon and the friction on the tires is balanced.

The cart experiences an unbalanced force from the air in the balloon and the friction on the tires.

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The shopping cart had more mass in Crash 2 than it did in Crash 1. In which crash did the skateboard experience a stronger force? Why? (Both carts experienced the SAME change in velocity)

The skateboard did not experience a force; only the shopping cart experienced a force in the crashes.

Crash 2; the force on the cart was stronger in this crash, so the force on the skateboard was also stronger.

The diagram doesn’t tell you anything about the force on the skateboard. It only gives information about the force on the shopping cart.

The skateboard experienced the same force in both crashes. The shopping cart changed speed by the same amount in each crash, so the force on the skateboard was the same each time.

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Some friends are playing a game called croquet. One player uses their mallet to hit their ball into another ball. The first ball slows to a stop, and the second ball starts rolling. The friends come up with explanations to describe energy movement in the scenario. Which friend is correct?

Jordan says that the force of the mallet only produced enough energy to move one ball at a time.

Jen says that energy from the the mallet was transferred to the first ball and then to the second ball.

Jackie says that the force of the mallet transferred a balanced force from the first ball to the second ball.

Jose says that energy from the force of the mallet increased in strength as it went from one d. Jose says that energy from the force of the mallet increased in strength as it went from one ball to the other one.

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A student is developing and testing a new design of a model car on a model track. She makes a graph to show the results of her test. How can the student develop a solution to increase the kinetic energy of the model car?

She would have to find a way to decrease the mass of the car.

She would have to add hills and turns to the same length of track.

She would have to find a way for the car to travel a longer ramp in the same amount of time.

She would have to find a way to increase friction between the wheels of the car and the track.

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Sandra pushed a wooden block and it slid across the floor. The wooden block gradually slowed down and stopped after moving 10 meters. Why did the block stop moving?

The floor exerted a force that is opposite to the direction of the block’s motion (friction).

The block ran out of force.

The floor absorbs force from the block.

All objects stop moving because their natural state is to be still.

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A Physical Education (gym) class is playing a game of soccer. During the game, the ball experiences a force of 0 newtons. Which statement explains what is most likely happening with the ball?

It is sitting still.

It is bouncing off someone’s knee.

It has been kicked across the field.

It has been tossed straight up into the air.

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In which trial will Object B travel the fastest?

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Two objects on the air hockey table are pushed toward each other. The objects are of equal mass. The sizes of the arrows are proportional to the acceleration. What is the most likely outcome of the collision?

Object A will move in the direction shown by Arrow B.

Object B will move in the direction shown by Arrow A.

Objects A and B will move in the direction shown by Arrow A.

Both objects will move in opposite directions to the ones shown by the arrows.

Both objects will move in the same directions as the ones shown by the arrows.

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Students explain why they chose a specific material as a liner for the safety helmet. Which of the following best explains the physics behind choosing a specific material as a liner? (Select all that apply)

a. For any given object, a larger force causes a larger change in motion.

b. An object’s motion will only change if the total force on it is balanced.

c. The mass of an object determines its change in motion when subject to a force.

d. The greater the mass of the object, the smaller the force needed to achieve any change in motion.

e. The force exerted by one object on a second object always moves the second object in the opposite direction.