Mechanics | Relativity Answers

when you are standing on the ground how much upward force is exerted on you by the ground?why does this force not lift you up?

in an experiment to find the young modulus , the strain should not be more than 1 in 1000 , explain this statement

A sprinter reaches his maximum speed in 2.5 seconds from rest with constant acceleration.He mantains
this speed and finishes 100 meters in over all time of 10.40 seconds. find his maximum speed.

A rod of length 56.0 cm and mass 1.40 kg is suspended by two strings which are 42.0 cm long, one at each end of the rod.

The string on side B is cut. Find the magnitude of the initial acceleration of end B.


The string on side B is retied and now has only half the length of the string on side A.

Find the magnitude of the initial acceleration of the end B when the string is cut.

A 90 kg person jumps from a 30 m tower into a tub of water with a volume of 5 m^3 initially at 20 degrees C. Assuming that all of the work done by the person is converted into heat to the water, what is the final temperature of the water?

According to Einstine's Theory of Relativity, time moves slower when we're closer to the ground (gravitational field). Here's the question. If one of an identical twin were to be raised on space station where time moves quicker, then after 10 years of Earth time - would they look different? Like will one of them look literally older than the other? thanks

I would like to know how much force is applied on a stop sign held by a person when the wind is 80 km/hour against it perpendicularly? The stop sign is 16" x 16" (or 40.64 cm square).

Q2:(a) What is the tangential acceleration of a bug on the rim of a 8.0 in. diameter disk if the disk moves from rest to an angular speed of 79 revolutions per minute in 4.0 s? (b) When the disk is at its final speed, what is the tangential velocity of the bug? m/s (c) One second after the bug starts from rest, what is its tangential acceleration? What is its centripetal acceleration? What is its total acceleration? ° (relative to the tangential acceleration)

Q1:Consider a level flight turn of a propeller-driven airplane in which the airplane makes a complete circular turn in 1.8 min. If the plane's speed is 200 m/s, what is the radius of the circle?
What is the centripetal acceleration of the plane?

Q1: A building superintendent twirls a set of keys in a circle at the end of a cord. If the keys have a centripetal acceleration of 121 m/s2 and the cord has a length of 0.25 m, what is the tangential speed of the keys?
Q2: A sock stuck to the side of a clothes-dryer barrel has a centripetal acceleration of 27 m/s2. If the dryer barrel has a radius of 26.0 cm, what is the tangential speed of the sock?
Q3: A grinding wheel 0.56 m in diameter rotates at 2500 rpm.
(a) Calculate its angular velocity in rad/s.
(b) What are the linear speed and acceleration of a point on the edge of the grinding wheel?
Q4: A rotating merry go-round makes one complete revolution in 4.3 s (Figure 8-38).
(a) What is the linear speed of a child seated 0.8 m from the center?
(b) What is her acceleration (give components)?
tangential acceleration:
radial acceleration:
Q5: (a) Find the centripetal accelerations of a point on the Equator, due to the rotation of Earth about its axis.
(b) Find the centripetal accelerations of at Nor