Mechanics | Relativity Answers

Does something, for example a tire or a shoe, wear out faster due to more friction on the road or will it wear out faster due to less friction? will a rougher surface wear out another more, or is it the slipperyness of the 2 surfaces that require more grip, hence wearing out each other more?

If a force of 80N extends a spring of natural lenght 8m by 0.4m what will be the lenght of the spring when applied force is 100n.

a lorry leaves a factory on a journey of 195 km at 08 45,travelling at an average speed of 52km/h.(b)On the return journey,the lorry leaves at 14 55 and arrives at factory at 18 15.Calculate the time taken and the average speed of the lorry on the return journey.

A diver has a mass of 75 kg takes part in a competition by having to perform 10 dives off the 10m platform above the water. Before he takes part he snacks on an energy bar (150 g) which provides 15 kj of energy. How many would the diver need to consume to meet the necessary energy to perform all 10 of his dives?

the pressure inside a 1.0cm radius vessel carrying blood with a speed of 0.50m/s is 5200 Newton/ square meter, while the pressure outside is 3200 Newton/ square meter. to what radius must the vessel be reduced so that the outside pressure is greater than that inside, thus making the vessel close at the constriction?

what is dynamics?

a box of mass 50kg is pulled up from the hold of a ship with an acceleration of 1m/s2 by a vertical rope attached to it.Find the tension in the rope what is the tension in the rope when the box moves up with a uniform velocity of 1m/s

A crate having a mass of 750kg is lifted from rest with a uniform acceleration by a crane such that after 10 seconds it has a velocity of 14m/s. Calculate the tension in the lifting cable.

Specific requirements:
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- The elastic limit of the steel forming a piece of wire is equal to 2.70 ×108 Pa. What is the maximum speed at which transverse wave pulses can propagate along this wire without exceeding this stress?( The density of steel is 7.86 × 103 Kg/m3

a square prism of wood 50*50 mm in cross section and 300 mm long is subjected to a tensile stress of 4 t/cm2 along it's longitudinal axis and lateral compressive to a tensile stress of 2 t/cm2 along one pair of sides and a lateral tensile stress of 1-0 t/cm2 acting along the other pair of sides.If the value of E of the material is 1.5*10 to the power 5 kg/cm2,calculate it's changed dimensions.poisson's ratio for wood=.4