Midterm Flashcards
(25 cards)
A block on a frictionless table….. the weight of the block on the moon
- m=f/a
- m= 90/7 = 12.86
- weight on moon = w = mxg
- g = gravity/acceleration shits on moon
- W = 12.86 x 1.62 = 20.8 = 21
A cart maintains a constant velocity of 100m/s for 10s. During this interval, acceleration is…
0m/s^2 (constant velocity = no acceleration)
An aircraft of a mass of 300,000kg has a speed of 22m/s during its landing. Break-in force is 430,000N. What is its speed 10s later?
- a = F/m
- a = 430000/300000 = 1.43
- velocity = acceleration x time
- V = 1.43 x 10 = 14.3
- she added 5 to the initial speed = 27-14.3 = 12.7
- but that no make sense to me so = 22-14.3= 7.7
A falling 1N apple hits the ground with a force of about
need more info
A hydralic pres has its input piston depressed 20cm, while the out piston is raised 1cm, and 1N input can lift a load of
- 1N x 20cm = 20 Mech Advantage
depression x force
A push on a 1kg brick accelerates it. Neglecting friction, equally accelerating 10kg brick requires
10 times as much force
An object of mass, m, rests on a flat table. The eart pulls on this object with a force of magnitiude mg. What is the reaction force to this pull?
the object pulls the earth up
A hypothetical planet has a mass of 1/2 that of the Earth, and a radius of twice that of the Earth. What is the acceleration due to gravity?
g = G(m/r^2) = G(m/(2R^2)) =
1/2 x 1/4 = g/8
A solid sphere, solid cylinder, and a hollow pipe, all of the same radii and mass are of uniform density. All three are released at the same time at the top of an incline. Which one will reach the ground first?
the solid sphere
A boy cannot balance on a seesaw with a fulcrum at its midpoint. If the fulcrum is moved to 1/4 the distance from the boy, balance is achieved when the weight of the boy is…
more than Ws (weight of the seesaw)
A rock is thrown from the edge of a tall cliff at some angle above the horizontal. It reaches the highest point and starts falling down. Which is correct?
Its horizontal component is the same as in the beginning
A boy kicks a football from ground level with an initial velocity of 20m/s at an angle of 60 degrees above the horizontal. What is the horizontal distance where the football hits the ground if we neglect air resistance?
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 dumbell shaped object is composed by two equal masses, m, connected by a rod of negligeable mass and length, r. If I1 is the moment of interia of this object with respect to an axis passing the center of the rod and perpendicular to it, and I2 is the moment of inertia with respect to an axis passing through on of the masses, then…
I2 > I1
Identical forces act for the same lengh of time on two different objects. The magnitude of the change of momentum of the lighter object is…
Exactly equal
A cat leaps to try to catch a bird. If the cat’s jump was at 60 degrees off the ground and initial speed was 3.48 m/s. What is the highest point of its trajectory, neglecting air resistance?
- Vy0^2/2g
- Vy0 = velocity x sin
- Vy0 = 3.48sin(60) = 3.01
- Vy0^2/2g = 3.01^2/(2)(9.81) = 0.46
If the force on the object is in the negative direction, the work it does on the object must be…
could be positive or negative depending on the direction of motion
Science is a body of knowledge that…
All of the above
Components of the vectors are given. What is the magnitude of the vector difference?
Ax - Bx = 7.6 - (-5.1) = 7.6 + 5.1 = 12.7
Ay - By = -9.2 - (-6.8) = -9.2 + 6.8 = -2.4
square root of (12.7)^2 + (-2.4)^2 = 12.9 = 13
The slope of the position versus time graph gives…
velocity
What is Fg on 69kg from m = 69kg at r = 14m?
Force = Gravity x mass1 x mass2/ distance apart^2
While flying horizontally in an airplane, you notice that a string dangling from an overhead luggage compartment hangs at rest at 15 degrees away from the vertical toward the front of the airplane. Using this observation, you can conclude that the airplane is…
accelerating backwards
When the distance between two stars decreases by 1/3, the force, Fg, between them…
*9 (is multiplied by 9, or 9 times the Fg)
When Keppler devised his laws of planetary motion he was most influenced by
Tyho Branche (his professor)
While you are standing in the isle of a bus, the driver suddenly makes a left turn. You lurch to the right due to…
Your tendency to keep moving forward (inertia)
