A car is driven at 80km/h on a horizontal road. If the car is now driven up a 10m high rise, what speed would it have at the top of the rise? (Assume that the wheels of the car roll at all times so that it doesn't experience sliding friction; exclude any other dissipative forces).

use the conservation of energy principles that the lady gave you

To determine the speed of the car at the top of the rise, we need to apply the principle of conservation of energy.

1. Convert the speed of the car from km/h to m/s.
- 80 km/h can be converted to m/s by multiplying by a conversion factor of 1000/3600.
- So, 80 km/h * (1000 m/1 km) * (1 h/3600 s) = 22.22 m/s.

2. Determine the potential energy at the bottom and top of the rise.
- The potential energy at a certain height is given by the formula: potential energy = mass * gravitational acceleration * height.
- Since the mass of the car is not given, we can safely assume it cancels out during calculations.
- At the bottom of the rise, the potential energy is 0, so we don't consider it in our calculations.
- At the top of the rise, the potential energy is given by: potential energy = mass * 9.8 m/s^2 * 10 m.

3. Apply the principle of conservation of energy.
- According to the principle of conservation of energy, the total mechanical energy of the system remains constant, assuming no dissipative forces are acting.
- Therefore, the initial kinetic energy (0.5 * mass * speed^2) at the bottom of the rise should equal the sum of the final kinetic energy and potential energy at the top of the rise.
- The final speed at the top of the rise can be found using the formula: final speed = sqrt( (2 * (potential energy at top of rise)) / mass).

4. Since the mass of the car cancels out, the final speed at the top of the rise is independent of the mass of the car. This means the final speed will be the same irrespective of the mass of the car.

So, to calculate the final speed at the top of the rise:
a) Calculate the potential energy at the top of the rise using the given height of 10 m.
b) Substitute the potential energy into the final speed formula.
c) Calculate the final speed.

Note: The answer will be the same regardless of the initial speed, as long as there are no dissipative forces acting.