Momentum, Impulse, CollisionsNewton’s Laws

Quiz Review Practice Problems/Questions

(Reminder: please don’t forget to also enter some responses for the Syllabus Statements related to momentum and impulse (listed in your WebQuest worksheets). These WILL be counted in your final score at the end of the mechanics unit when the books are collected (mid-January). You will NOT receive a completion stamp for them.)

Reminders

•WebQuest worksheets due tomorrow in class

•WebAssigns are due tomorrow before 1st period

•Task 3 power point (remember, rubric is online in the WebQuest instructions!) is due tomorrow by 11:59 PM!

•Quiz covers Newton’s laws, Momentum, Impulse, and Conservation of Momentum (including collisions).

Question 1

•If a 55.0 kg woman is riding in a car traveling at 90.0 km/h, what is her linear momentum relative to:▫The ground?

▫The car?

Question 1~~Answer

•If a 55.0 kg woman is riding in a car traveling at 90.0 km/h, what is her linear momentum relative to:▫The ground?

▫The car?

smkg

s

h

km

m

h

kmkgmvp

13801375

3600

1

1

1000

1

0.90)0.55(

smkg

smkgmvp 0)00.0)(0.55(

Question 2

•A 13.5 kg lamp is hung from the ceiling using 2 cables. What is the tension in the cables if:

▫The cables are both hung vertically?

▫The cables are both hung so they make an angle of 63.5° with the ceiling?

Question 2~~Answer

•A 13.5 kg lamp is hung from the ceiling using 2 cables. What is the tension in the cables if:▫The cables are both

hung vertically?

NF

kgF

mgF

FFF

F

T

sm

T

T

gTT

y

2.662

)81.9)(5.13(

2

0

0

2

21

Question 2~~Answer•A 13.5 kg lamp is hung from the ceiling

using 2 cables. What is the tension in the cables if:▫The cables are both hung so they make an

angle of 63.5° with the ceiling?

NSin

NF

kgSinF

mgF

F

T

sm

T

Ty

y

0.74)5.63(2

)4.132(

)81.9)(5.13()5.63(2

2

0

2

Question 3

•How fast would a 1160 kg car travel (in m/s)if it had the same linear momentum as a 1570 kg truck traveling at 90.0 km/h?

Question 3~~answer•How fast would a 1160 kg car travel (in

m/s)if it had the same linear momentum as a 1570 kg truck traveling at 90 km/h?

sm

car

sm

truckcar

truckcar

v

kgvkg

vmvm

pp

8.331160

39250

)0.25)(1570())(1160(

)()(

s

mtruck

kmm

hkm

truck

vs

hv

0.25

)36001)(1000)(0.90(

Question 4

•A 0.150 kg baseball traveling with a horizontal speed of 5.00 m/s is hit by a bat and then moves with a speed of 42.4 m/s in the opposite direction. What is the change in the ball's momentum?

Question 4~~Answer•A 0.150 kg baseball traveling with a

horizontal speed of 5.00 m/s is hit by a bat and then moves with a speed of 42.4 m/s in the opposite direction. What is the change in the ball's momentum?

smkg

sm

sm

if

p

p

kgp

vvmp

vmp

11.7

)4.47()150.0(

))00.5(4.42)(150.0(

)(

Question 5

•A 15.0 g rubber bullet hits a wall with a speed of 150 m/s. If the bullet bounces straight back with a speed of 125 m/s, what is the change in momentum of the bullet?

Question 5~~Answer•A 15.0 g rubber bullet hits a wall with a

speed of 150 m/s. If the bullet bounces straight back with a speed of 125 m/s, what is the change in momentum of the bullet?

smkg

sm

sm

if

p

p

kgp

vvmp

vmp

13.4

)275()015.0(

))150(125)(015.0(

)(

Question 6

•A person pushes a 12.3 kg box from rest and accelerates it to a speed of 2.17 m/s with a constant force. If the box is pushed for a time of 2.35 s, what is the force exerted by the person?

Question 6~~Answer•A person pushes a 12.3 kg box from rest

and accelerates it to a speed of 2.17 m/s with a constant force. If the box is pushed for a time of 2.35 s, what is the force exerted by the person?

NF

kgsF

vmtF

sm

4.11

)17.2)(3.12()35.2(

Question 7

•A loaded tractor-trailer with a total mass of 3200 kg traveling at 2.0 km/h hits a loading dock and comes to a stop in 0.64 s. What is the magnitude of the average force exerted on the truck by the dock?

Question 7~~Answer•A loaded tractor-trailer with a total mass

of 3200 kg traveling at 2.0 km/h hits a loading dock and comes to a stop in 0.64 s. What is the magnitude of the average force exerted on the truck by the dock?

NNF

F

kgsF

vmtF

sh

kmm

hkm

28008.2777

8.1777)64.0(

))(1000)(0.2)(3200()64.0( 36001

Question 8

•A 1.32 kg mud ball drops from rest at a height of 10.0 m. If the impact between the ball and the ground lasts 0.604 s, what is the average net force exerted by the ball on the ground?

Question 8 ~~Answer•A 1.32 kg mud ball drops from rest at a

height of 10.0 m. If the impact between the ball and the ground lasts 0.604 s, what is the average net force exerted by the ball on the ground?

NF

kgsF

vmtF

sm

6.30

)0.14)(32.1()604.0(

?

604.0

32.1

?

0

81.9

0.10

0

2

F

st

kgm

v

v

a

md

sm

smv

v

advv

0.142.196

)0.10)(81.9(20

222

20

2

Question 9

•A 0.5 kg ball is thrown horizontally with a velocity of 15 m/s against a wall. If the ball rebounds horizontally with a velocity of 13 m/s and the contact time is 0.025 s, what is the force exerted on the ball by the wall?

Question 9~~Answer

•A 0.5 kg ball is thrown horizontally with a velocity of 15 m/s against a wall. If the ball rebounds horizontally with a velocity of 13 m/s and the contact time is 0.025 s, what is the force exerted on the ball by the wall? 𝐹 ∙∆ 𝑡=𝑚 ∙∆𝑣

𝐹 ∙ (0.025 𝑠 )=(0.50𝑘𝑔 ) ∙(13𝑚𝑠 −(−15𝑚𝑠 ))

𝐹=14

𝑘𝑔𝑚𝑠

0.025𝑠=560𝑁

Question 10• A one-dimensional impulse force acts on a 4.50 kg

object as diagrammed in the figure below.

• (a) What is the magnitude of the impulse given to the object?

(b) What is the magnitude of the average force?

(c) What is the final velocity if the object had an initial speed of 5.80 m/s in a direction opposite to the impulse force?

Question 10~~Answer•A one-dimensional impulse force acts on a

4.50 kg object as diagrammed in the figure below.

•(a) What is the magnitude of the impulse given to the object?

Impulse = area under the lineImpulse = (Impulse = (0.5)(0.14+(0.08-0.05))·900

•Impulse = 76.5 N·s

Question 10~~Answer•A one-dimensional impulse force acts on a

4.50 kg object as diagrammed in the figure below.

•(b) What is the magnitude of the average force?

Impulse = F·Dt(76.5 N·s) = F·(0.14s)546 N = F

F = 550 N

Question 10~~Answer•A one-dimensional impulse force acts on a

4.50 kg object as diagrammed in the figure below.

(c) What is the final velocity if the object had an initial speed of 5.80 m/s in a direction opposite to the impulse force?F·Dt=m·Dv(76.5 N·s)=(4.50 kg)(vf – (-5.80m/s))

Question 11•A 16000 N automobile travels at a speed of

50 km/h northward along a street, and a 9000 N sports car travels at a speed of 64 km/h eastward along an intersecting street. (a) If neither driver brakes and the cars collide at the intersection and lock bumpers, what will the velocity of the cars be immediately after the collision? (magnitude AND direction)

Question 11~~Answer•A 16000 N automobile travels at a speed of 50

km/h northward along a street, and a 9000 N sports car travels at a speed of 64 km/h eastward along an intersecting street. (a) If neither driver brakes and the cars collide at the intersection and lock bumpers, what will the velocity of the cars be immediately after the collision?

Step 1: determine the mass of each carStep 2: determine the momentum of each carstep 3: draw your vector diagram! Each car is a component of the total final momentum

Question 11~~Answer•A 16000 N automobile travels at a speed of 50 km/h

northward along a street, and a 9000 N sports car travels at a speed of 64 km/h eastward along an intersecting street. (a) If neither driver brakes and the cars collide at the intersection and lock bumpers, what will the velocity of the cars be immediately after the collision? m1=16000 N/9.81 m·s-2=1631 kgm2=9000 N/9.81 m·s-2=917 kgp1=m·v=(1631 kg)·(50km/h)(1000m/km)(1h/3600s)

p1=22650 Nsp2=m·v=(917 kg)·(64km/h)(1000m/km)(1h/3600s)

p2=16302 Ns

Question 11•A 16000 N automobile travels at a speed of

50 km/h northward along a street, and a 9000 N sports car travels at a speed of 64 km/h eastward along an intersecting street. (a) If neither driver brakes and the cars collide at the intersection and lock bumpers, what will the velocity of the cars be immediately after the collision?

p(final)=

226

50 N

s

16302 Ns

=