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An object with weight w is suspended from two strings at angles θ1 and θ2 to the vertical and with tensions T1 and T2. How would you resolve the vertical and horizontal forces?

Horizontal: T1 sin θ1 = T2 sin θ2Vertical: T1 cos θ1 + T2 cos θ2 = w

Answered by Heather W. • Physics tutor

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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: mcdT = dE where m is mass, c is specific heat capacity and dT is the change in temperature.
Time taken is calculated...

Answered by Benjamin C. • Physics tutor

5280 Views

If a wire loop moves at constant speed into a region where there is a magnetic field, why is a current induced in the wire?

In this question, a square wire loop of length L and resistance R starts in a region with no magnetic field, and moves at a speed v into a region with magnetic field B, which is acting perpendicular to th...

Answered by Gus B. • Physics tutor

1923 Views

From what height, h, should a rail-cart fall to complete a loop-the-loop of radius r without falling off a the track? Assume the track on which the rail-cart travels is smooth and express h in terms of r.

This question combines the principles of energy conservation and circular motion. The insight is to realise the condition for which the rail-cart will fall off of the track - when there is no contact forc...

Answered by Benjamin R. • Physics tutor

1119 Views

A box initially at rest is on a plank, of length 5m, that is elevated at an angle such that tan(a)=3/4. When it reaches the end of the plank it has velocity 5ms^-1. Calculate the average frictional force on the box.

In physics questions it is useful to not plug numbers in until the end and instead work through algebraically. Let's say the angle of elevation is a, the mass is m, the velocity at the end of the plank is...

Answered by • Physics tutor

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