Search our library of Physics questions

Top answers

Physics

All levels

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...

Answered by Alice D. • Physics tutor

5436 Views

A kettle boils 0.6kg of water. After some time the temperature of the water has decreased to 83 degrees. The specific heat capacity of water is 4200J/kg. Calculate the energy transferred to the surroundings.

The variables we are given are mass (m), time (t), temperate CHANGE (delta T) and SHC (c) and we are asked for energy. Think of the equations for energy we know: mgh, 1/2mv², mcdeltaT...the fir...

Answered by Alice D. • Physics tutor

2119 Views

What are the definitions of a)voltage and b)current?

a) Current is defined as the rate of flow of charge; I = Q/t (Current is charge/time).b) Voltage is an electromotive force which drives the charge around the circuit. A potential difference between two po...

Answered by Shrey C. • Physics tutor

1720 Views

Why can light travel through space but sound cannot?

Light is a transverse wave whose oscillations are perpendicular to its direction of movement. It is on the electromagnetic spectrum, so it does not need particles to propagate through. It can propagate t...

Answered by Adeoluwa P. • Physics tutor

12494 Views

A car of mass 1500kg is travelling at 10 ms-1 along a horizontal road. A brake force of 3000N brings it to rest. Calculate the deceleration of the car and the distance travelled by the car whilst decelerating.

To calculate the deceleration of the car we must re-arrange F=ma to make a the subject of the formula, a = F/m. We then put in the numbers to get, 3000/1500, to get a deceleration of 2 ms^-2.
To get...

Answered by • Physics tutor

5761 Views