Which statements about braking a car are true? a)the greater the kinetic energy of a car, the longer it takes for the car to stop. b) the lower the kinetic energy of a car, the longer it takes for the car to stop. c)if the speed of a car doubles, the car’s kinetic energy and braking distance quadruple. d)if the speed of a car doubles, the car’s kinetic energy and braking distance remain the same.

What is the earliest point in the universe that we can observe? why can’t we see back further than this?

The of a machine determines its "usefulness." a. input force b. output force c. mechanical advantage

Ablock of mass m = 2.5 kg is attached to a spring with spring constant k = 710 n/m. it is initially at rest on an inclined plane that is at an angle of θ = 23° with respect to the horizontal, and the coefficient of kinetic friction between the block and the plane is μk = 0.19. in the initial position, where the spring is compressed by a distance of d = 0.16 m, the mass is at its lowest position and the spring is compressed the maximum amount. take the initial gravitational energy of the block as zero. a) what is the block's initial mechanical energy? b) if the spring pushes the block up the incline, what distance, l, in meters will the block travel before coming to rest? the spring remains attached to both the block and the fixed wall throughout its motion.