3 Basic Physics Questions?

Question

1. Before Galileo's time, what forces were people aware of? and during Galileo's time what forces did he discover relating to physics?


2. What physical quantity is a measure of the amount of inertia an object has?


3. You are having trouble starting your car. A friend offers to give you a push. A second friend comes along and also offers to help. How does the acceleration change when two people push compared to when only one person pushes?

Answer 1

1- gravity , elastic forces (as in bows and catapults), Archimedes' push - In Galileo time was discovered air pressure (Torricelli experiment)

2- Mass

3- Forces add up for the same mass, then acceleration also adds up : F1 is force from friend 1, A1 is acceleration/thrust given by him
F1= m.A1
F2= m.A2

F1 + F2 = m. (A1 + A2)

Answer 2

1. I you sure he didn't mean Newton. As far as I can recall Galileo didn't discover any forces. He dicovered gravity accelerated objects at equal rates regardless of their size or mass. He built telescopes and stated the sun was at the center of our solar system until the Catholic Church arrested him and forced him to recant under threat of torture. Before galileo there was an awareness of magnetism "loadstone", but not electricity, gravity, nor the strong or weak nuclear forces. In short, before Galileo's time, none. Galileo gave Newton the largest contributions to his discovery of gravity and susequent mathmatical relationship.

2. Momentum

3 F=ma, or a = F/m; You need to know the mass of the car, the mass of your friends and the force they can apply individually and together to answer precisley. Assuming both are the same size and strength and that the mass of the car far exceeds their mass, the acceleration is effectively doubled.

Answer 3

one million. the on the spot the guy threw the rock, many of the capability could be switched over and not be 'used' as an acceleration of the guy and boat interior the choice direction. with the aid of fact the boat strikes interior the water (in reaction) and the guy interior the air, a number of this capability and momentum could be dissipated, additionally. finally, with the aid of fact the rock pushed its way via the air, it may lose momentum. via the time it finally landed its momentum could be much less. So the real answer is confident. i've got confidence your instructor probable needs you to ignore approximately all of those genuine outcomes and answer No, momentum is conserved. 2. individual A could ought to hit it with a view to make it holiday as rapid as conceivable interior the choice direction. considering that's no longer a given option, and because "deflect it" is undefined, i do no longer understand which answer your instructor believes is actual. My hypothesis is "seize it" considering that ought to flow each and all of the kinetic capability interior the rock to the skateboarder+rock gadget. you will word you do no longer technically get "speed" from the rock; you get momentum flow, you get capability flow - you don't get speed flow! i ponder whether your instructor is a moron.... as long as you deflect it making use of individual A's capability then you certainly gets greater momentum interior the choice direction. it ought to truly finally end up the optimal direction of deflection, to wring out the main 'speed' isn't a opposite of the inward trajectory, with the aid of fact the mechanics of the 'swing' ought to additionally be taken under consideration. an extremely poorly conceived question, with out sparkling answer. 3. finally one with a quite sparkling and unambiguous answer. For a spherically symmetric planet, the acceleration of gravity in any respect distances above the exterior is set via the equation a = Gm/r² the place r is the area from the middle of the planet (r >= Rs, the place Rs is the radius of the planet) m is the mass of the planet and G is the primary Gravitational consistent. For a given mass m', the stress of gravity is given via F = m'a. Do the maths. (ie F/f = m'A/m'a = A/a = GM/R² ÷ Gm/r² = Mr² / (mR²) ) the place top case is planet 2 and decrease case is planet one million

Answer 4

1. Not many.
2.Its Mass
3.Acceleration is doubled assuming
force due to second person equals that
of the first person.

Answer 5

1. no idea
2. no idea
3. no idea