PLEASE HELP FAST!! What makes a model not useful? a)if it is in proportion with the object it represents
b)if it is made of a different material than the object it represents
c)if it is not the same mass of the object it represents
d)if it is out of proportion with the object it represents

Ajogger runs 5.0 km on a straight trail at and angle of 60 south of west . what is the southern component of the run rounded to the nearest tenth of a kilometer

Examine the equation. 23490th→23088ra+42he what kind of barrier would you need to block the radioactive particles from this reaction? a. a piece of paper b. a sheet of aluminum foil c. a two-inch block of lead d. a solid concrete block

Aperson gives a shopping cart an initial push along a horizontal floor to get it moving, and then lets go. the cart travels forward along the floor, gradually slowing as it moves. consider the horizontal force(s) on the cart while it is moving forward and slowing. which of the following statements is correct? (a) both a forward and a backward force are acting on the cart, but the forward force is larger. (b) only a forward force is acting which diminishes with time. (c) both a forward and a backward force are acting on the cart, but the backward force is larger. (d) only a backward force is acting, no forward force.