Forces TestFriday, November 20, 2015

Friday, 11/20Unit 4: Forces Last chance to turn in missing work for the forces unit! Respond to the following on your warm-up:

A 20 kg child is at rest on the ground. For each situation below draw a free body diagram (to scale), calculate the forces acting on the child, and describe the motion (direction and acceleration).

1. Calculate the child’s weight.

2. The child decides to climb a rope on a play ground. The child accelerates at 0.40 m/s2. Calculate the force of tension in the rope.

3. As the child climbs upwards, the force exerted by the rope is changed to 198 N. Calculate the new acceleration of the child.

Upcoming dates Friday, 11/20 – Last day to turn in late work Friday, 11/20 – unit 4 test W/O 11/23 – Thanksgiving Break Friday, 12/11 - Nine week extra credit due by 4:00 PM

Friday, 11/20Unit 4: Forces

A 20 kg child is at rest on the ground. For each situation below draw a free body diagram (to scale), calculate the forces acting on the child, and describe the motion (direction and acceleration).

Calculate the child’s weight.

G: m = 20.0 kg E: Fg = (m)(ag) S: Fg = 196 N

ag = 9.8 m/s2

U: Fg S: Fg = (20)(9.8)

Child is at rest, forces are balanced, and acceleration is zero.

Friday, 11/20Unit 4: Forces

The child decides to climb a rope on a play ground. The child accelerates at 0.40 m/s2. Calculate the force of tension in the rope.

G: m = 20.0 kg E: Fnet = (m)(a) S: Fnet = 8 N

a = 0.40 m/s2

Fg = 196 N

U: Fnet S: Fnet = (20)(.40)

FT = Fg + Fnet

FT = 196 + 8

FT = 204 N

Child is moving upwards, forces are unbalanced, and acceleration is 0.40 m/s2

Friday, 11/20Unit 4: ForcesA 20 kg child is at rest on the ground. For each situation below draw a free body diagram (to scale), calculate the forces acting on the child, and describe the motion (direction and acceleration).

As the child climbs upwards, the force exerted by the rope is changed to 198 N. Calculate the new acceleration of the child.

G: FT = 198 N E: Fnet = (m)(a) S: a = .10 m/s2

Fg = 196 N

Fnet – 2N (198-196)

m = 20 kg

U: a S: 2 = (20)(a)

Unbalanced forces, moving upward, accelerating at .10 m/s2

Test Pick up a calculator

If you have a smiley face on your review, put your review on the front lab table.

Put your phone in your bag. Phone not in your bag equals cheating – No questions asked.

Take a breath…you can do this!

You can write on the test.

When finished, turn in your test to the front After the test do the following:

Pick up a Chrome Book Go to my website for today’s date and click on the ‘momentum’ link. On the back of your warm-up respond to the following

In your own words describe momentum. If you were going to create an equation to represent momentum what variables

would you include. Hold onto your Chrome Book…we are going to put them back all together

Turn your warm-up in (black tray) Find something quiet to do until everyone is finished (you can keep the Chrome Book but no phones…may be a good time to do Membeam)