The position of a 2 kg object is given as x(t) = Bt2 +5, where x is in meters and t is in seconds. (a) Determine the force F responsible for this motion. (3) (b) If the force only results in a change in the kinetic energy of the object of 200 J between tı = 0 s and t2 = 5 s, determine the value of B. (3) (C) Without using kinematics (equations of motion), determine the displacement of the object during these 5 seconds referred to in part (b). (2)

An ideal spring has a spring constant (force constant) of 2500 n/m, is stretched 4.0 cm, how much elastic potential energy does it possess? (a) 3j (b) 0.00j (c) 1j (d) 2j (e) 4j

Consider an ordinary, helium-filled party balloon with a volume of 2.2 ft3. the lifting force on the balloon due to the outside air is the net resultant of the pressure distribution exerted on the exterior surface of the balloon. using this fact, we can derive archimedes’ principle, namely that the upward force on the balloon is equal to the weight of the air displaced by the balloon. assuming that the balloon is at sea level, where the air density is 0.002377 slug/ft3, calculate the maximum weight that can be lifted by the balloon. note: the molecular weight of air is 28.8 and that of helium is 4.

An electric current is flowing through the cord below. what will happen to this current if a magnet is brought near the cord? a. the electric current will stop flowing. b. it will exert a force on the voltage. c. the resistance of the wire will decrease. d. it will exert a force on the electric current.