# physics

A discus thrower (with arm length of 1.2 m) starts from rest and begins to rotate counterclockwise with an angular acceleration of 3.0 rad/s2.
(a) How long does it take the discus thrower's speed to get to 4.5 rad/s?

(b) How many revolutions does the thrower make to reach the speed of 4.5 rad/s?
revolutions

(c) What is the linear speed of the discus at 4.5 rad/s?

(d) What is the tangential acceleration of the discus thrower at this point?

(e) What is the magnitude of the centripetal acceleration of the discus thrown?

(f) What is the magnitude of the discus's total acceleration?

1. 👍 0
2. 👎 0
3. 👁 223
1. I will be happy to critique your thinking on this.

1. 👍 0
2. 👎 0
👨‍🏫
bobpursley
2. a) 4.5/3= 1.5 s
b) i'm still confused of how to get the number of revolutions
c) a=v^2/r the answer is 5.4 m/s
d) at=r alpha but we need to find alpha first to get at

1. 👍 0
2. 👎 0
3. b, displacement= 1/2 angacceleration*time^2

d.total acceleartion: find centripetal acceleration (v^2/r) That is inward. No tangentail acceleration is 3*r

those are at ninety degrees, add them as vectors (Pythagorean theorem_

1. 👍 0
2. 👎 0
👨‍🏫
bobpursley
4. i just want to find the number of revolutions , i know that 2 pi rad= 1 rev but how do we find that in this question.

1. 👍 0
2. 👎 0

## Similar Questions

1. ### Physics

A tortoise and hare start from rest and have a race. As the race begins, both accelerate forward. The hare accelerates uniformly at a rate of 0.8 m/s2 for 4.4 seconds. It then continues at a constant speed for 13.5 seconds, before

2. ### Physics

A wheel mounted on a stationary axle starts at rest and is given the following angular acceleration: 9-12t where t is the time after the wheel begins to rotate. Find the number of revolutions that the wheel turns before it stops (

3. ### physics

an astronaut rotates at the end of a test machine whose arm has a length of 10.0m. if the acceleration she experiences must not exceed 5g (g=10m/s^2? what is the maximum number of revolutions per minute of the arm?

4. ### Algebra

a tuxedo rental shop rents tuxedos with sleeve lengths from 20 inches to 40 inches. The shop says the length of the sleeves should be about 1.2 times a person's arm length. Write and solve a compound inequality that represents the

1. ### physics

A small coin, initially at rest, begins falling. If the clock starts when the coin begins to fall, what is the magnitude of the coin\'s displacement between t1 = 0.1749 s and t2 = 0.437 s?

One end of a thin rod is attached to a pivot, about which it can rotate without friction. Air resistance is absent. The rod has a length of 0.59 m and is uniform. It is hanging vertically straight downward. The end of the rod

3. ### Phy 231

A CD-Rom starts from rest and undergoes uniform angular acceleration until it reaches 26,000 rpm in 0.25 s. Through what angle does it rotate during this time?

4. ### college

The arm in the figure below weighs 44.5 N. The force of gravity acting on the arm acts through point A. Determine the magnitudes of the tension force t in the deltoid muscle and the force s of the shoulder on the humerus

1. ### Physics

A small coin, initially at rest, begins falling. If the clock starts when the coin begins to fall, what is the magnitude of the coin\'s displacement between t1 = 0.230 s and t2 = 0.517 s?

2. ### Physics

If a discus thrower rotates through the last 45 degrees of a turn in .11 seconds and the distance from the axis of the rotation to the center of the discus is 1.22 m, what is the average linear velocity of the discus?

3. ### physics

The flywheel of a steam engine begins to rotate from rest with a constant angular acceleration of 1.45 rad/s2. It accelerates for 29.5 s, then maintains a constant angular velocity. Calculate the total angle through which the

4. ### physics

a modified U-tube: the right arm is shorter than the left arm. The open end of the right arm is height d = 10.0 cm above the laboratory bench. The radius throughout the tube is 1.60 cm. Water is gradually poured into the open end