Question

Questions on horizontal circular motion. Any help appreciated =)

Horizontal circular motion questions:

1. if net force of an object is constant in magnitude and always directed perpendicular to its velocity, the speed of an object is
a. decreasing
b. increasing
c. zero
d. constant

2. The net force on a vehicle traveling at a constant speed on a curved path points
a. in the direction of motion
b. to the center of curvature
c. opposite the direction of motion
d. away from the center of curvature

Answer 1

3. an airplane is flying with constant speed of 300 m/s in a horizontal circle with a radius of 15,000 m. If the lift force of the air on the wings is perpendicular to the wings, at what angle relative to the horizontal should the wings be banked?
a. 15.1 degrees
b. 22.2 degrees
c. 31.5 degrees
d. 37.7 degrees
e. 63 degrees

4. if the radius of the space station is 90m, how fast would the station have to rotate so that passengers on the outer edge experience a centripetal acceleration of 10 m/s^2?
a. 30 m/s
b. 9 m/s
c. 900 m/s
d. 3000 m/s

Answer 2

I feel like 1 is constant and 2 is to the center of the curvature?

Answer 3

Can I help you?

Answer 4

yes any help is appreciated i am struggling haha

Answer 5

1. From Newton's Second Law \[\sum F = ma\]If the force is perpendicular to the motion and the motion is rigidly constrained to that path, we know that the velocity must remain constant. Think about a train. If a cross wind blows perpendicular to the track, the train doesn't slide sideways, instead is remains on the track. This wind does not the affect the motion of the train along the track.

If the motion isn't constrained, this force will obviously cause as increase in velocity, since \(a \gt 0\). Think about a tumble weed rolling down a hill.

Number 1 is a little vague and ambiguous, so you'll have to use your judgement on it. Seeing as this related to circular motion, I would agree with you that the correct choice is constant.

You are correct about number 2.

Answer 6

For question 3. I'll refer you here: http://www.batesville.k12.in.us/physics/phynet/mechanics/circular%20motion/banked_no_friction.htm

Consider that since an airplane doesn't make contact with any surface, the no friction case is required to maintain the desired radius of curvature.

Answer 7

Of course, I'm glad to answer any questions you may have regarding the explanation given at the link.

Answer 8

For question 4. The centripetal force is defined as\[F_C = m {v^2 \over r}\]Noting that\[a_c = {v^2 \over r}\]\[\therefore m a_c = m {v^2 \over r}\]

I don't like the way this question is worded either. The speed at which the space station rotates should be given as angular velocity, not tangential velocity. Only the portion of the space station at a radius of 90m rotates at the velocity, not the space station as a whole. Give your teacher a hard time for me! :-)

Answer 9

I looked at the link and I feel like #3 is 31.5 or 37.7?

Answer 10

And yes my teacher always has vague wording in his questions which makes it hard

Answer 11

The wording of question 4 isn't so much vague as it is wrong. Question 1 is vague, at best. The wording never gets any better, we just get better at understanding what the teacher wants. :-)

Answer 12

Ok thanks. Yes is #3 one of those two answers?

Answer 13

and #4 would be 30?

Answer 14

One of those two is correct.

Answer 15

30 is correct for #4

Answer 16

I got 31.5 by using tan and 37.7 using sin. I'm assuming it's 31.5 for the answer?

Answer 17

tangent is correct.

Answer 18

okay thank you so much!