1.If a block weighs 30 pounds and has a static friction of .7 and a sliding friction of .55 and Fn=Fw
a. How much force must be applied to just cause motion?
b. Once motion has begun what force must be maintained to cause constant velocity motion?
2.A plank is tilted slowly to an angle of 30 degrees with a 12 pound block on it
Find FN, FF and the static friction?
3.A force of 26lbs. causes impending motion. If the force is maintained at 26lbs.Fn=Fw=65lbs and the sliding friction is .28.
find:
a.mass of the block
b.FF
c.acceleration
What force must be maintained to cause an acceleration of 2ft/s^2?
1. (a) (weight)x (static friction coefficient)
(b) (weight) x (kinetic friction coefficient)
I will he glad to critique your work on the other two questions. You will usually get quicker responses here by posting one question at a time.
To answer these questions, we need to understand the concepts of friction, weight, and Newton's second law of motion. Let's break down each question and explain how to find the answers step by step.
1. If a block weighs 30 pounds and has a static friction of 0.7 and a sliding friction of 0.55, and Fn = Fw:
a. How much force must be applied to just cause motion?
To find the force required to just cause motion, we need to overcome the static friction. The maximum static friction force can be calculated using the formula: F_static = static friction coefficient * Fn.
Given that the static friction coefficient is 0.7 and Fn = Fw (weight), which is equal to 30 pounds, we can calculate:
F_static = 0.7 * 30 = 21 pounds
Therefore, a force of at least 21 pounds must be applied to just cause motion.
b. Once motion has begun, what force must be maintained to cause constant velocity motion?
Once motion has begun, we are dealing with sliding friction (kinetic friction). The sliding friction force can be calculated using the formula: F_kinetic = kinetic friction coefficient * Fn.
Given that the sliding friction coefficient is 0.55 and Fn is still equal to Fw (weight), which is 30 pounds, we can calculate:
F_kinetic = 0.55 * 30 = 16.5 pounds
Therefore, a force of 16.5 pounds must be maintained to cause constant velocity motion.
2. A plank is tilted slowly to an angle of 30 degrees with a 12-pound block on it. Find FN, FF, and the static friction?
To find FN (normal force), we need to consider the forces acting perpendicular to the surface, which include the weight of the block. The normal force is equal to the weight of the block when the block is on a level surface.
FN = Fw = weight = 12 pounds
To find FF (force of friction), we need to consider the forces acting parallel to the surface. At this angle, the force of friction can be found using the formula: FF = friction coefficient * FN.
Since the question doesn't provide a specific friction coefficient, we cannot determine FF without that information. Please provide the friction coefficient to calculate FF.
3. A force of 26 pounds causes impending motion. If the force is maintained at 26 pounds, FN = Fw = 65 pounds, and the sliding friction is 0.28, find:
a. The mass of the block
To find the mass of the block, we can use Newton's second law of motion: F = m * a, where F is the force, m is the mass, and a is the acceleration. In this case, the given force is 26 pounds, and the weight of the block (which is equivalent to the normal force) is 65 pounds.
Therefore, 26 pounds = m * a. But since a is the acceleration due to gravity (approximately 32 ft/s^2), we can rewrite the equation as:
26 pounds = m * 32 ft/s^2
To find mass (m), we rearrange the equation:
m = 26 pounds / 32 ft/s^2
The mass of the block is the value obtained from this calculation.
b. FF (force of friction)
To find FF, we need to use the sliding friction coefficient provided, which is 0.28, and the normal force (FN or Fw), which is 65 pounds.
FF = friction coefficient * FN
FF = 0.28 * 65 pounds
The calculated value will be the force of friction (FF).
c. Acceleration
To find the acceleration, we can use the formula F = m * a, where F is the force and m is the mass. The force causing the motion is the force applied, which is 26 pounds.
26 pounds = m * a
From this equation, we can solve for a, which represents the acceleration.
What force must be maintained to cause an acceleration of 2 ft/s^2?
Since we already determined the mass of the block, we can use the equation F = m * a to find the force required to cause a specific acceleration. In this case, the acceleration is 2 ft/s^2, and the mass is the value obtained in question 3a.
F = m * a
F = mass * 2 ft/s^2
The calculated value will be the force required to cause the given acceleration.