a.) A hockey puck is observed to be sliding along a flat frictionless surface at
ID: 2004817 • Letter: A
Question
a.) A hockey puck is observed to be sliding along a flat frictionless surface at a speed of 4 cm/min. There is no net force acting on the puck. Assuming it doesn't smash into anything, how fast will the puck be going 17 min later?cm/min
b.) An object is accelerating. Which one of the following statements is true?
The object must be speeding up.
Gravity must be causing the object to accelerate.
The object must be changing directions.
The object must be slowing down.
There is a net force acting on the object.
c.) A 100 kg block weighs 220 lb on Earth. If the block were transported to a planetary body that had a smaller free fall acceleration (as compared to Earth), which one of the following would be true?
The block would have the same weight and a smaller mass.
The block would have the same mass and a bigger weight.
The block would have the same mass and the same weight.
The block would have the same weight and a bigger mass.
The block would have the same mass and a smaller weight.
d.) What does it mean (in physics) to say that a quantity is conserved?
It means that the quantity is not being used.
It means the total amount is zero.
It means the total amount never changes.
It means it's being saved up.
e.) At a certain point in time, the total energy of a closed system is observed to be 176 J. Which one of the following statements is true?
Three hours later the energy of the system is 352 J.
Four hours later the energy of the system is 88 J.
All of the energy must be kinetic if the objects are moving.
Twelve hours later the energy of the system is 176 J.
Some of the energy must be potential.
g.) Which of the following statements are impossible? Choose all that apply.
The parked truck had 8770 J of KE.
The scooter had 0 J of KE and 0 kg·m/s of momentum.
A ball moving in a circle had 0 N of net force acting on it.
A box had an acceleration of 0 m/s2 while a net force of 311 N acted on it.
Jack exerted 18 N of force due east on a cart. As a direct result, the cart exerted 18 N of force due west upon Jack.
A toothpick exerts a smaller gravitational force upon the Moon than the Moon exerts upon it.
a.) Two balls make up a closed system. Ball A has 701 J of energy and ball B has 78 J. After they collide, ball A has 665 J. How much energy does ball B have after they collide?
J
b.) An asteroid and a comet collide head on. Prior to the collision, the asteroid has a momentum of 700,000 kg·m/s up and the comet has a momentum of 800,000 kg·m/s down. After the collision the asteroid has a momentum of 750,000 kg·m/s down. After the collision, what is the comet's momentum?
kg·m/s
North
South
East
West
Up
Down
Left
Right
No direction because the comet has stopped
c.) How much does a 28 kg object weigh on Moon? Please feel free to reference the Solar System Data table located at the beginning of Unit II.
______N
d.) A 660 N net force acts on a 42 kg object. Determine the object's acceleration.
_____m/s2
e.) Calculate the gravitational force between a 657 kg object (resting on Earth) and the Moon. The mass of the Moon is 7.347×1022 kg and the distance between the object & the Moon is 3.844×108 m.
____N
Explanation / Answer
a) 4 cm/min b) there is a force acting on it [f=ma, if a is not zero, f is not zero] c) same mass, smaller weight [ mass is constant regardless of g, weight depends on g] d) the amount doesnt change [quantity in the beginning = quantity in the end] e) 12 hrs later, it is still 176J [same as above explanation] g) the parked truck one [ke = .5mv^2. v=0 since its parked, ke must be 0] a)114J [701 + 78 = 665 + x] b)650,000 kg m/s up [net initial = net final] c)4.48 N [28 kg * 1.6m/s^2] d)15.71 m/s^2 [660/42] e)2.179x10^-2 [gm1m2/r^2]
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