Worksheet for Chapter 8B
(Round 3 decimal places)
1. Melanie and Amy are trying to push a 40 N box up a 23˚ ramp. Find the minimum
amount of force they need to use in order to keep the box from sliding down the
ramp.
2. A weight of 150 pounds rests on an incline of 20 . What is the minimum magnitude
of force of friction.
3 A Pontiac Bonneville with a gross weight of 4500 pounds is parked on a street with
 to keep the car from rolling down the hill.
a slope of 10˚. Find the force required
4. Two forces of 25 and 15 pounds act on a body so that the angle between them is an
angle of 75˚. Assume that the 25 pound force is acting on the positive x-axis. Find
the magnitude of the resultant.
5. Two forces, one of 35 pounds and the other of 50 pounds act on the same object.
The angle between the forces is 30˚. Find the magnitude of the resultant vector of
these two forces.
6. Two forces, one of 100 pounds and the other of 150 pounds, act on the same
object at angles of 20˚ and 60˚ respectively with positive x-axis. Find the
magnitude of the resultant of these forces.
7. An airplane’s velocity with respect to the air is 580 mph and its headed N 58 W .
The wind is blowing to the northeast and has a velocity of 60
mph. What is the direction of the plane and what is its speed with respect to
the ground.
8. A jet is heading due north with an airspeed of 500mph, and the wind is blowing
to the southeast at 50mph. What is the ground speed of the jet?
9. A little girl is pulling a red wagon with the force of 50 pounds. How much work is
done in moving the wagon 100 feet if the handle makes an angle of 30˚ with the
ground.
(Use the formula for work, W = FD, where F is the horizontal component of force
and D is the horizontal distance)
10. A plane’s heading is 160˚ and its air speed is 350 mph. If a west wind is blowing at
20mph, what is the plane’s ground speed? What is the direction of the plane?
ANSWERS
1. 15.629 N
2. 51.303 lbs
3. 781.417 lbs
4. 32.313 lbs
5. 82.195 lbs
6. 235.545 lbs
7. 569.511 mph; N 52.108º W
8. 465.988 mph
9. 4330.127 foot-pounds
10. 357.335 mph ; S 23.015º E