Quiz 2 Flashcards
(25 cards)
Determine recoil speed
velocity of cannonball - weight of cannon x its unknown velocity
100x57- 1200v =0
solve for v
A cart rolling, crane drops ore
impulse formula: p=mv
velocity = total mass of cart and ore x ijts unknown velocity
1200x10.8 = 1880v
solve for v
A rocket explodes into 2 fragments….The magnitude of the momentum of the lighter one is?
The same
A ver light ping pong ball moving east @ 4m/s….. which onject experiences greater impulse?
Both (the same impulse for both)
When you jump from an elevated position…. the time of the contact about 10 times that of a stilt legged landing…. average force on body from the ground is?
about 1/10
A 4kg object with v of 2m/s and a 1 kg object with v of 4 m/s… Which traveled the greater distance?
do equation V^2M or velocity squared times mass
2^2(4) = 16
4^2 (1) = 16
both/ same
A ball is thrown horizontally from the top of a tower at the same instant a stone is dropped vertically. Which object travels faster when it hits the ground?
the ball
A toy elevator is raised from the ground from ground floor to 2nd floor in 20s. The power needed using 1000g of work is?
power formula: p=work/time
1000/20s = 50 w
How much work would a child so while pulling a 12kg wagon a distance of 3.2m with 22N force?
Work formula: Force x distance
22n x3.5m = 77J
Which pulls on the oceans if the earth with a greater force?
Sun
Which pulls on the tides with a greater force?
Moon
You do 121j of work while pulling your sister back on a frictionless swin… your sisters mass is?
vertical displacement formula:
d = Length cos(degree)
find cos (32) = .8480
d= 5.1 x .8480 = 4.325 m
work = mass x gravity x height
121 = ? x 9.81 x 4.325
to find mass = work/gravity x height
m= 121/9.8 x 4.325 = 6.51
A block slides down a frictionless inclined ramp…. Find the speed of the block when it reaches the ground
velocity = square root of 2gh
height = length x cos(degree)
36sin(19) = 11.72
v= sqaure root of 2 x 9.81 x 11.72 =15.2
A force of 12N is applied to the end of 0.63m long torque range @ 45 degrees… What is the magnitude of the torque?
arm/length = sin(degree)
arm/0.63 = sin(45)
solve for arm
arm = 6.3sin(45)
torque = force x lever arm
= 6.3sin(45) x 12N = 5.3Nm
Machinist t=0, it accelerates uniformly for 10s and reaches rate of angular speed of 75 radians/sec…..What is the number of rotations?
Change in theta:
time of acceleration x (angular speed/2) + time speed was maintained x angular speed + 31.25 x (angular speed/2)
10 x (72/2) + 25 x 75 + 31.25 x (75/2) = 3421.872 radians
1 rad = 1 rev/2 pi
= 3421.872/ 2 pi = 540
Gravitational force of venus on earth
Force = Gravity x mass1 x mass2/ distance apart^2
Planet A has twice the mass of Planet B. What can we conclude about the acceleration of the due to gravity at the surface of A compared to that of surface B?
Need to know radii
Two small balls, A and B, attached each other gravitationally with a force of magnitude of F. If we double both masses and the separation of the balls, what will now be the magnitude of the attractive force on each one?
1F =F
What is the gravitational force acting on a 53kg person due to another 53kg person?
F = gravity x mass1 x mass2/ distance apart^2
A boy kicks a football from ground level with an initial velocity of 25m/s…. Find the range
Range = Vxo x Tair (2Tmax)
Vxo= velocity x cos(degree)
= 25cos(70) = 8.5505
Tmax = velocity x sin(degree)/ gravity
= 25sin (70)/9.81 = 2.3947s
Range= 8.5505 x (2 x 2.3947) = 40.95 = 41
A boy throws a ball with an initial speed of 25 m/s… How high is the ball after 2 secs?
V0yt = speed x sin(degree)
= 25sin(30) = 12.5
V0yt -gt^2/2
12.5 - (9.81 x 2^2)/2 = 5.4
A spinning ice skater on extremely smooth ice is able o control the rate at which she rotates by pulling her arms. Which of the following is true?
Her angular momentum remains the same
Consider a uniform a hoop of radius, R, and a mass, M, rolling without slipping. Which is larger, its translational kenetic energy or it rotational kenetic energy?
both are equal
James and John dive from an overhang into the lake. Jake simply drops. Jogn takes a running start with 25 m/s horizontal speed in the beginning. Compare the time it takes to the lake.
both at the same time
