Assignment #1 HK 376 – Biomechanics
January 11, 2016
1. -1.6 rads/s is equal to how many degrees/s? (1)
2. 422 degrees is equal to how many radians? (1)
3.
a)
b)
c)
d)
e)
The difference between speed and velocity is (1)
speed considers not only the rate of motion but the direction of motion
velocity considers not only the rate of motion but the direction of motion
velocity can be calculated using of displacement while speed uses distance
Both b and c
Both a and c
4. A hockey puck is shot down the ice in the positive x direction. The puck slows down
as it travels along the ice due to the friction between the puck and the surface of the
ice. In what direction is the puck’s velocity? In what direction is the puck’s
acceleration? (1)
5. Jeff and Matt once got into a fist fight. After trading jabs for a few seconds, they
each decided that it was time to throw a ‘haymaker.’ Jeff’s arms are longer than
Matt’s. If each fighter threw his ‘roundhouse’ punch with the same angular velocity,
whose hand would be moving faster? What kinematic equations support your
answer? Jeff and Matt no longer fight. (1)
6. Describe in detail how displacement, velocity, and acceleration are related? (2)
7. What is the angle θ and the length X for the triangle below? (1)
8. Willy sprints 300 m West, stops, and jogs 400 m East
a. What distance did he cover? (1)
b. What was his average velocity if it took him 120 s? (1)
9. With her arms out, a figure skater spins with an angular velocity of 30 rads/s. She then
pulls her arms in and undergoes an average angular acceleration of 60 rads/s/s for
1.2 s. What is her final angular velocity after the 1.2 seconds of acceleration? (1)
10. The head of a golf club has an angular velocity of 1150 degrees/sec and a
tangential velocity of 21.1 m/s at the point of impact with the golf ball. How far away
is the head of the club from the point of rotation? (1)
11. Determine the average velocity for an Olympic 400 sprinter that runs in the inside
lane of a 400m lap in 47 seconds? (1)
12. Kenny jogs 5 km North and then 10 km West. What was his displacement? (1)
13. In a game against the St. F.X. Xmen, a Dalhousie hockey player picks up the puck at
the corner of the icing line and the East side boards. He skates the puck 20 feet up
the ice (North) before getting crushed by Xmen defenseman. If the Dalhousie
hockey player was hit by the StFX defenseman 12 feet from the east side boards,
what was his displacement prior to the hit (answer in m)? (1)
14. Caid Mile Failte! The Town and County of Antigonish is proud to be home to the
world’s longest running Highland Games outside Scotland. One of the weekend’s
highlights is the Scottish Heavy Events. Mayor Carl Chisholm’s favourite event is the
‘28lb Weight for Distance.’ In this event, a 12.7 kg weight is attached at the end of a
0.52 m chain. This year’s Champion, Greg Hadley, was spinning about an axis that
ran vertically straight through the center of his body. The distance (radius) from
Greg’s spin axis to his outstretched hands that were gripping the start of the chain’s
handle was 0.68 m. The weight was being whirled around with an instantaneous
angular acceleration of 26 rad/s/s about his spin axis.
a. What is the “effective radius” for the weight at the end of the cable? (1)
b. What is the component of linear acceleration acting orthogonally to the radius in
m/s/s? (1)
15. ‘Flip’ crosses the finish line with a velocity of 9 m/s. He takes 3 s to come to a
complete stop. What was his average acceleration over the 3 s? (1)
16. During a jump, a figure skater has an average angular velocity of 45 rads/s while in
the air. If the skater completes 2.5 rotations, how much time did she spend in the air
before landing? (1)
_____
19
This assignment is due at the beginning of class on Monday January 18th, 2012.
Please show all your work and BOX your answers.