Phys204 Week 3 Book Assignment

Chapter 5 pg 143

1. Mass 6.00 kg moved by 18.0N. What is its acceleration?

F=ma Divide both sides by m

a=Fm

a=18N/6.00kg convert N = 18N * 1kg*m/s^2 = 18kg*m/s^2

a=18kg*m/s^2/ 6.00 kg = 3m/s^2

a=3m/s^2

7. Truck pulls trailer with friction force of 870 N and a coefficient of friction 0.23. What is the trailer’s normal force.

Ff=μFN

870N=.023(FN) divide by .023

FN=870N/.023

FN=37826.7N

9. mass 13.0 kg dropped from a cliff. Find its weight

Fw=mg

Fw=13.0kg * 9.8m/s^2

Fw=127.4kg*m/s^2

Fw=127.4N

13. A force of 175N needed to keep a 640N engine from sliding. What is the coefficient of static friction?

Ff=μFN

Ff=175N

FN=640N

175N=μ640N divide by 640N

µ=175N/640N

µ=.273

1400Kg

1400Kg

2100N-425N=1675N

a=F/m

a=1675N/1400kg=1675kg*m/s^2/1400kg=1.2m/s^2

2100N-425N=1675N

a=F/m

a=1675N/1400kg=1675kg*m/s^2/1400kg=1.2m/s^2

15. find acceleration of a forklift mass 1400kg pushed by force 2100N opposed by frictional force of 425N.

2100N

2100N

a = ??

a = ??

425N

425N

Chapter 6 page 163

3. Box pushed with a force 125 N for 2.00 min. What is the impulse?

impulse=Ft

Impulse=125N*120s

Impulse=15000Ns=15000(kg*m/s^2)(s)

Impusle=15000kg*m/s

7. 15.0g bullet fired. Muzzle velocity 3250m/s from a rifle with mass 4.74kg and barrel length 75.0 cm.

A) How long is bullet in barrel? d/s=t

B) what is the force on the bullet while in the barrel? Ft=mvf-mvi

C) Find the bullet’s momentum as it leaves barrel. p=mv

a) t=75cm/3250m/s 100cm=1m 75cm/1* 1m/100cm= .75m

t=.75m/3250m/s=2.307E-4s

time in barrel is 2.307E-4 seconds

b) F=mvf-mvit

F=15.0g3250ms-15.0g0ms2.307X10-4

F=15.0g*3250ms/2.307X10-4s

F=48750g*m/s/2.307X10-4s=48.750kg*m/s/2.307X10-4s

F=211313.394kg*m/s2 X 1N/1kg*m/s2=211313.394N

211,313.394N of force on the bullet as it leaves the barrel.

c) p=mv

p=15.0g * 3250m/s

p=48.75kg*m/s

m1v1+m2v2=m1v’1+m2v’2

(575g*3.05m/s)+(425g*0m/s)=(575g*v’1)+(425g*4.03m/s)...