# DYN.B Acceleration Original Assignment Part 1Name

**DYN.B – Acceleration – Original Assignment – Part 1Name:**

**Acceleration and Circular Motion**

Conceptual

Review:

1.Accelerating objects are _____. Choose the one mostinclusive answer.

a. going fastb. speeding up (only)

c. speeding up or slowing downd. changing their velocity

2.Identify the three controls on an automobile that are responsible for causing the car to accelerate.

**Acceleration and Circular Motion:**

3.A car that is moving in a circle at a constant speed of 30 mi/hr is _____.

a. not accelerating since there is no change in velocity

b. not accelerating despite the fact that there is a change in velocity

c. accelerating since there is a change in velocity

d. accelerating despite the fact there is no change in velocity.

e. accelerating, but not for either reason mentioned above.

4.An object that is moving in a circle at a constant speed has a velocity vector that is directed ______and an acceleration vector that is directed ______.

a. tangent to the circle, tangent to the circleb. tangent to the circle, outwards

c. tangent to the circle, inwards d. inwards, tangent to the circle

d. inwards, outwardsf. outwards, tangent to the circle

5.An object moves in a clockwise direction along the circular path as shown in the diagram at the right. Three points along the path are labeled - A, B and C. For each location, draw a straight-line vector arrow in the direction of the velocity vector; label this vector as v. Then draw a straight-line vector arrow in the direction of the acceleration vector; label this vector as a. /6.An object that is moving in uniform circular motion will definitely have a large acceleration if it is _____.

a. moving very fast

b. moving along a sharp turn

c. turning at a rapid rate

Justify your answer:

**Interesting Fact:**

The moon orbits about the Earth with an average speed of just over 1000 m/s; yet its acceleration is less than 0.003 m/s2. The moon is a fast-moving object with a low acceleration.

Calculations

- A 500 kg mass is spun in a circle of radius 25 m with a velocity of 250 m/s. What is its acceleration?

- What is the acceleration of an object that has a velocity of 25 m/s and is moving in a circle of radius 10m?

- What is the acceleration of an object that has a velocity of 37 m/s and is moving in a circle of radius 45m?
- During the spin cycle of a washing machine, the clothes stick to the outer wall of the barrel as it spins at a rate as high as 1800 revolutions per minute. The radius of the barrel is 0.26 m.
- a. Determine the speed of the clothes (in m/s) which are located on the wall of the spin barrel.

b. Determine the acceleration of the clothes.

5. Elmira, New York boasts of having the fastest carousel ride in the world. The merry-go-round at Eldridge Park takes riders on a spin at 18 mi/hr (8.0 m/s). The radius of the circle about which the outside riders move is approximately 7.4 m. Determine the acceleration of the riders.

6. Alexis is in her Toyota Camry and trying to make a turn off an expressway at 19.0 m/s. The turning radius of the level curve is 35.0 m. Her car has a mass of 1240 kg. Determine the acceleration

7. A manufacturer of CD-ROM drives claims that the player can spin the disc as frequently as 1200 revolutions per minute. What is the acceleration of the outer row of data if this row is located 5.6 cm (0.056m) from the center of the disc?

*You will have to find tangential velocity first*

8. In the display window of the toy store at the local mall, a battery-powered plane is suspended from a string and flying in a horizontal circle. The 631-gram plane makes a complete circle every 2.15 seconds. The radius of the circle is 0.950 m. Determine theacceleration.

*You will have to find tangential velocity first.*

9. In an effort to rev up his class, Mr. H does a demonstration with a bucket of water tied to a 1.3-meter long string. The bucket and water have a mass of 1.8 kg. Mr. H whirls the bucket in a vertical circle such that it has a speed of 3.9 m/s at the top of the loop and 6.4 m/s at the bottom of the loop.

Determine the acceleration of the bucket at each location.

10. A boy is whirling a rock attached to a string overhead in a horizontal circle. The rock makes a complete loop in 0.50 s and the string is 0.60 m long. Find the centripetal acceleration of the rock.

*You will have to find tangential velocity first.*

Answers Conceptual

1.Accelerating objects are **__changing their velocity__**. Choose the one mostinclusive answer.

a. going fastb. speeding up (only)

c. speeding up or slowing down**d. changing their velocity**

2.Identify the three controls on an automobile that are responsible for causing the car to accelerate.

Use of the gas pedal allows one to speed up. Use of the brake pedal allows one to slow down. And use of **the steering wheel** allows one to change directions.

**Acceleration and Circular Motion:**

3.A car that is moving in a circle at a constant speed of 30 mi/hr is _____.

a. not accelerating since there is no change in velocity

b. not accelerating despite the fact that there is a change in velocity

**c. accelerating since there is a change in velocity**

d. accelerating despite the fact there is no change in velocity.

e. accelerating, but not for either reason mentioned above.

NOTE: Accelerating objects are changing their velocity. And the velocity of an object is the speed with a direction. Moving in a circle involves a changing direction and thus a changing velocity.

4.An object that is moving in a circle at a constant speed has a velocity vector that is directed **__tangent to the circle__** and an acceleration vector that is directed __inwards__.

a. tangent to the circle, tangent to the circleb. tangent to the circle, outwards

**c. tangent to the circle, inwards**d. inwards, tangent to the circle

d. inwards, outwardsf. outwards, tangent to the circle

5.An object moves in a clockwise direction along the circular path as shown in the diagram at the right. Three points along the path are labeled - A, B and C. For each location, draw a straight-line vector arrow in the direction of the velocity vector; label this vector as v. Then draw a straight-line vector arrow in the direction of the acceleration vector; label this vector as a.NOTE: The velocity vector should be drawn tangent to the circle and the acceleration vector should be directed towards the center of the circle. /

6.An object that is moving in uniform circular motion will definitely have a large acceleration if it is **___turning at a rapid rate___**.

a. moving very fast

b. moving along a sharp turn

**c. turning at a rapid rate**

Justify your answer:

An object can be moving very fast yet have such a wide turning radius that it has a very small acceleration; the moon is an example. Another object can be moving along a very sharp turn yet so slowly that its acceleration is very small; a slow moving truck along a tight expressway ramp is an example. For objects moving in circles, acceleration is most closely linked to the rate of direction change - that is, to the turning rate. A rapid turning rate may be due to either a high speed or a sharp turn or both.

Calculations Answers

- 2,500 m/s2
- 62.5 m/s2
- 30.4 m/s2
- a. 49 m/sb. 9.2 x 103 m/s/s
- 8.7 m/s/s
- 10.31 m/s/s
- 8.8 x 104 cm/s/s or 8.8 x 102 m/s/s
- 8.11 m/s/s
- TOP: 12 m/s/s, down

BOTTOM: 32 m/s/s, up

**Academic Physics 2013 – Anderson HSPage 1**