Ablock is hung by a string from the inside roof of a van. when the can goes straight ahead at a speed of 28 m/s, the block hangs vertically down. but when the van maintains this same speed around an unbanked curve (r = 150m), the block swings toward the outside of the curve. the string makes an angle θ with the veritcal. find θ.

θ =28.07⁰

Explanation:

when van moves around an unbanked curve, horizontal component of normal force is equal to centripetal force

---(1)

There is no motion in vertical direction, so vertical component of normal force is balanced with weight of block i.e.

----(2)

divide (1) and (2)

v = 28 m/s

r = 150 m

g = 9.8m/

θ = 28.07⁰

0.55x745.7j and a calculator

answer would be letter choice (a),   a ball resting on a shelf. would be another example of potential energy   >   stored energy > not moving.

a ball spinning on a finger   >   kinetic energy > moving energy

a ball rolling on the ground   >   kinetic energy   > moving energy

a   ball flying through the air   > kinetic energy   >   moving energy

hope that                                         : )