PHYS 0847 Lecture 3: Physics - Chapter 2.5, Chapter 3

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greyleopard748

9 Mar 2017

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A fo(cid:396)(cid:272)e is (cid:396)e(cid:395)ui(cid:396)ed to (cid:272)ha(cid:374)ge a(cid:374) o(cid:271)je(cid:272)t"s (cid:448)elo(cid:272)ity. If a force acts on an object, it will keep moving in the same direction at a constant velocity. The te(cid:374)de(cid:374)(cid:272)y of a(cid:374) o(cid:271)je(cid:272)t to (cid:396)esist (cid:272)ha(cid:374)ges i(cid:374) (cid:373)otio(cid:374) is (cid:272)alled (cid:862)i(cid:374)e(cid:396)tia(cid:863). The effect of a force on an object is less if it has larger mass. It is easier to change the motion of a lighte(cid:396) o(cid:271)je(cid:272)t. mass (cid:373)easu(cid:396)es a(cid:374) o(cid:271)je(cid:272)t"s resistance to changing its motion. If an object exerts a force on you, then you exert an equally strong force on it. Forces always come in pairs an action and a reaction. Whe(cid:374) a (cid:396)o(cid:449)e(cid:396) pushes (cid:449)ate(cid:396) (cid:271)a(cid:272)k(cid:449)a(cid:396)ds, the water pushes the boat forwards. When gravity pulls down on you, you are pulling the earth up and with equal strength. The ea(cid:396)th (cid:271)a(cid:396)ely (cid:373)o(cid:448)es i(cid:374) (cid:396)espo(cid:374)se to (cid:373)y fo(cid:396)(cid:272)e (cid:271)e(cid:272)ause its (cid:373)ass is so la(cid:396)ge (cid:894)ne(cid:449)to(cid:374)"s (cid:1006)nd law).

Related Questions

Suppose you attach the object with mass m to a vertical spring originally at rest, and let it bounce up and down. You release the object from rest at the spring’s original rest length. (a) Show that the spring exerts an upward force of 2.00 mg on the object at its lowest point. (b) If the spring has a force constant of 10.0 N/m and a 0.25-kg-mass object is set in motion as described, find the amplitude of the oscillations. (c) Find the maximum velocity.

greyjackal98

Most of us know intuitively that in a head-on collision between a large dump truck and a subcompact car, you are better off being in the truck than in the car. Why is this? Many people imagine that the collision force exerted on the car is much greater than that exerted on the truck. To substantiate this view, they point out that the car is crushed, whereas the truck is only dented. This idea of unequal forces, of course, is false; Newton’s third law tells us that both objects are acted upon by forces of the same magnitude. The truck suffers less damage because it is made of stronger metal. But what about the two drivers? Do they experience the same forces? To answer this question, suppose that each vehicle is initially moving at 8.00 m/s and that they undergo a perfectly inelastic head-on collision. Each driver has mass 80.0 kg. Including the masses of the drivers, the total masses of the vehicles are 800 kg for the car and 4.00 × 10³ kg for the truck. If the collision time is 0.120 s, what force does the seat belt exert on each driver?