{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

exam 2 key

# exam 2 key - Question 21 Bens mass is 100 kg He lands from...

This preview shows pages 1–2. Sign up to view the full content.

Question 21 Ben’s mass is 100 kg. He lands from a jump. His initial vertical velocity when his feet first touch the ground is 4 m/s downward. What is the average normal contact force that acts on Ben’s feet during this landing if he comes to a stop in 0.20 s? (3 pts) Given Answer: mass=100 kg (weight 981N) F– t = m(v f - v i ) F (.20s)= (100kg)(0m/s--4m/s) F= 2000N + 981N (don’t forget to consider gravity, similar to the problem with the basketball player from the homework) F= 2981 N acting upward Question 22 Amy is in-line skating. She is rolling forward (north) on a flat section of road at 10 m/s. Her mass is 50 kg. The rolling friction acting on the wheels of her skates is 10 N backward (south). Air resistance creates a 15 N force also acting backward (south) on her. If these are the only horizontal forces acting on Amy, what is her horizontal acceleration as a result of these forces? (2 pts) Given Answer: Forces acting against Amy= 10 N from friction = 15 N air resistance Total= 25 N South (since Amy is traveling North) F = ma -25N= (50kg)a a= -.5m/s 2 or .5 m/s 2 south (backward) ( don’t forget to include direction)

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

### Page1 / 3

exam 2 key - Question 21 Bens mass is 100 kg He lands from...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document
Ask a homework question - tutors are online