A car driver has to make an emergency stop. The braking distance depends on the speed of the car. For the same braking force, what happens to the braking distance if the speed doubles?
For a situation like this it is best to think of the energy of the car!The car has a kinetic energy = 1/2mv2 so if the speed has doubled the new kinetic energy of the car will be 1/2m(2v)2 meaning the kinetic energy has increased by a factor of 4. To top the car work must be done by the brakes. The work done will also have gone up by a factor of 4. As work = f x d and the force is the same, the braking distance will have increased by a factor of 4.
AD
Related Physics GCSE answers
All answers ▸A cricket player throws a ball such that it travels 10 meters in 2 seconds at constant acceleration. Calculate the kinetic energy of the ball if it has a mass of 1kg.
What actually is current? Why does it differ from potential difference?
A person swims from a depth of 0.5m to 1.7m below the surface of the sea. Denisty Sea Water = 1030 kg/m^3. g=Gravitational Field Strength = 9.8 N/kg. Calculate the change in pressure on the swimmer and give the unit.
I throw a ball straight up with an initial velocity of 2m/s. How high is it after a fifth of a second?