A truck with a mass of 400 kg is moving down the highway at a constant speed. When the driver sees a red light, the brakes are used to slow down at an acceleration of −0.7 m/s2. Using the equation F = ma, what force must the brakes exert for the truck to slow at that rate? Round your answer to the nearest whole number.

The brakes must exert a force of

An electron and a proton are held on an x axis, with the electron at x = + 1.000 m and the proton at x = - 1.000 m. part a how much work is required to bring an additional electron from infinity to the origin? express your answer with the appropriate units. part b if, instead of the second electron coming in from infinity, it is initially at x = + 20.00 m on the axis and is given an initial velocity of 100.0 m/s toward the origin, does it reach the origin? part c how close to the origin does it come?