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The intensity of sound heard by Jonathan when his headphones is “on” his ear is around \ (3.6x10-4 W/m2 \). Assuming the initial distance is around 4.6cmwhen the headphone is on his ear, what is the intensity when he removes the headset, and is a distance 7.4cm from his ear?
Note: Use this notation in writing units with exponents that are more than one: s2 = s2
A 25kg child sits in a swing that is attached to ropes 1.6 m long. Find the potential energy of the child relative to his lowest position when the ropes are horizontal.
A rubber band has a spring constant of 45N\m. If the rubber band is pulled by a force of 9.8N, (a) how far would it stretch?(b)what is the worked done by this force in stretching this string
A horizontal force F applied to an object varies with its displacement. (Force is 4.0) Calculate the work done by the force when the object moves from x =0 to x=10.0m.
A shopper pushes her 25 kg grocery cart by a force of 225 N inclined at an angle of 60° with the horizontal through a distance of 7.5 m . Find the worked done by (a) the 255 N force and (b) friction. Assume that the coefficient of kinetic friction is 0.32
there are 500m3 of air in a shop at 20°c. what is the difference in volume if the temperature is 0°c
A christmas ball in a shape of a hollow sphere is hung from the tree by a piece of trade attached to the surface of the ball the mass and radius of the tall are 0.105 kg and 0.12 m respectively what will be its period of rotation when slightly displaced from its equilibrium position
Block A is at rest on a frictionless incline. It is attached to block B over a pulley. Block A has mass of 4.50 kg and block B has a mass of 5.50 kg. When the system is released, block A moves up the incline 1.5 m, after which it has a speed of 3.00 m/s.
3. Seat belt
In the event of an accident, a car driver (80kg) will use the seat belt (and because of
the crumple zone) over a distance of 40cm from 72 km / h to a standstill
braked. This takes 40 ms = 0.040 s.
a) Calculate the braking force on the driver.
b) When supporting on the steering wheel, you can "apply" a maximum of 500 N.
Would that be enough to protect yourself without a seat belt?
Estimate the number of hairs on your head.
I used an interesting estimation which is to say that 1cm2 = 100 hairs and to estimate the head as sphere with radius of r = 10 cm.
Am I right to tell an estimation like this?
If not what is right??
