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It takes 4200 Joules to heat up 1 kg of water by 1 C^o. If you have a kettle with a power of 2500 Watts, how long will it takes to boil 0.8 kg of water from an initial temperature of 25 C^o to the nearest second??

Energy required calculated using the equation for specific heat capacity: m c dT = dE where m is mass, c is specific heat capacity and dT is the change in temperature. Time taken is calculated using the rela...
BC
Answered by Benjamin C. • Physics tutor
7837 Views

A ball of mass 500g is dropped from rest 2m above the ground. When it reaches the ground it is travelling at 5m/s. How much energy has been dissipated?

Initial energy (Gravitational Potential): E = mgh = 0.5 x 9.81 x 2 = 9.81J Final energy (Kinetic): E = mv 2 /2 = (0.5 x 5 2 )/2 = 6.25J Energy lost = 9.81 - 6.25 = 3.56J
GB
Answered by Georgina B. • Physics tutor
2484 Views

A person has a suitcase with wheels. The person pulls the suitcase with a horizontal force of 13 N for 110 m. Calculate the work done on the suitcase by the person (3 marks).

Work done = force x distance moved Work done = 13 N x 110 m Work done = 1430 J
JT
Answered by Jasmine T. • Physics tutor
5340 Views

Does a negative acceleration always mean that the object is slowing down?

Sometimes, but definitely not always! Note: it's all dependent on which direction has been assigned '+'. Acceleration is a vector quantity , (the rate of change of velocity), meaning it has both magnitude an...
RG
Answered by Rohan G. • Physics tutor
18682 Views

A car travels 100 metres in 20 seconds. i) What is the cars speed? ii) How far would the car travel in 1 minute 40 seconds?

To answer this question, we will need the following equation: SPEED = DISTANCE/TIME (A multiplication and division triangle will be shown)i) The speed of the car is calculated by doing 100 metres/ 20 seconds...
DH
Answered by Delwar H. • Physics tutor
21603 Views