Question

PY 217 GENERAL PHYSICS CALCULUS-BASED Final Exam Name Part A TOTAL Part C Part B Score USE OF SMARTPHONE DURING EXAM IS PROSCRIBED PART 1: WORK ENERGY Problem A1: A person applies a horizontal force of 200N to a 40kg crate that moves 2m along a 5º incline. Find the work on the crate F = 200N 40kg 1) By the person 2) By the friction if x = 0.25 3) By gravity 4) Using the work energy theorem find the final speed if the final speed if the crate starts from rest.

Answer 1

here,

1)

horizontal force , F = 200 N

mass of crate ,m = 40 kg

s = 2 m

theta = 5 degree

a)

the work done by the person , Wp = F * s * cos(theta)

Wp = 200 * 2 * cos(5) J= 398.5 J

b)

uk = 0.25

the normal force , N = m * g * cos(theta) + F * sin(theta)

the work done by friction force , Wff = (-1) * uk * N * s

Wff = - 0.25 * (m * g * cos(theta) + F * sin(theta)) * 2 J

Wff = - 0.25 * (40 * 9.81 * cos(5) + 200 * sin(5)) * 2 = - 204.2 J

c)

the work done by gravity , Wg= - m * g * s * sin(theta)

Wg = - 40 * 9.81 * 2 * sin(5) J

Wg = - 68.3 J

d)

let the final speed be v

using Work energy theorm

Wp + Wff + Wg = 0.5 * m * ( v^2 - 0)

398.5 - 204.2 - 68.3 = 0.5 * 40 * v^2

solving for v

v = 2.51 m/s

the final speed is 2.51 m/s