# Physics questions?

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I just got my physics test back and am trying to review this stuff …can some1 help me correct the answers (given my incorrect ones)Thx!

1.A car that is turning a corner at constant speed:

a)must have an net external force acting on it

b)is accelerating

c)has a constant velocity

My ans: b

2.A “10-pound bag” of potatoes has a mass of abt 4.54kg. If I take them to the moon, the bag of potatoes:

a) will still weight 10 pounds

b)will still have a mass of 4.54kg

c)will weight much less than 10 pounds

d)will have a mass of much less than 4.54kg

My ans: b,c,d

1. An obj falling through the air at a constant, “terminal velocity”:

a)is in “free-fall”

b)is not accelerating

c)has a net force of zero acting on it

My ans: a,c

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4.An obj is thrown straight upward from the earth’s surface. Assume free fall and that the acceleration due to gravity is 10m/sec/sec (down). Over the time interval from one second before the highest point to one second after the highest point, the total change in veloci

• 1) both a and b are correct. You are accelerating, which means you must have a net force acting on you.

2) b and c are correct. d contradicts b. Why would you put that?

3) b and c are correct. “Freefall” is not well-defined here, so you might even make a case for a. Once you are at terminal velocity, the air resistance equals the weight, so the net force is zero, so there is no acceleration, so your speed is constant.

4)

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RE:

Physics questions?

I just got my physics test back and am trying to review this stuff …can some1 help me correct the answers (given my incorrect ones)Thx!

1.A car that is turning a corner at constant speed:

a)must have an net external force acting on it

b)is accelerating

c)has a constant velocity

My ans:…

• 1) a-correct. Because there must be a force pointing turning center ( circular motion)

b-correct. accelerating because the change in the direction of velocity creates ecceleration even if speed is constant.

c-correct

2) In moon weight decreases but mass does not change as mass is amonut of matter.

so b and c correct

3) a,b,c is correct. As in terminal velocity, weight and air friction are equal so net force is zero. If force is zero, acceleration is also zero. And in free fall an object can reach terminal velocity as falling.

4) One second before and after, the height and speed are equal but the directions of speeds at two points are opposite.

• 1. c

1. c
2. b, c

4. zero, if you throw a ball up and catch it at the exact same hieght it will hit the same amount or force you threw it with. 