Mechanics | Relativity Answers

Speedy Sue, driving at 33.0 m/s, enters a one-lane tunnel. She then observes a slow-moving van 175 m ahead traveling with velocity 5.10 m/s. Sue applies her brakes but can accelerate only at -2.00 m/s2 because the road is wet. Will there be a collision?If yes, determine how far into the tunnel and at what time the collision occurs. If no, determine the distance of closest approach between Sue's car and the van and enter zero for the time.

A block of wood weighs 46.2 N in air. A sinker is hanging from the block, and the weight of the wood-sinker combination is 235.8 N when the sinker alone is immersed in water. When the wood-sinker combination is completely immersed, the weight is 115.8 N. Find the density of the block.

A 0.20 kg stone is held 2.0 m above the ground and then dropped .
1- find the stone's total mechanical energy at the point where it is dropped.
2- find the stone's total mechanical energy when it reached to the ground.
3- find the stone's speed at a height of 0.7m from the ground .
4- find the stone's speed when it reached to the ground .
5- find the height at which the stone's speed is 3.0 m/s

The displacement of a block attached to a horizontal spring whose spring constant is 6 N/m is given by


x = 0.4 \cos(4.1 t - 0.8) m.


What is the earliest time (t > 0) when the kinetic energy equals one-half the potential energy?

If Bill stands up from a chair with wheels it will roll backwards. Is the chair's momentum more, less or equal to Bill's momentum?

At 21C, an aluminum ring has an inner diameter of 8 cm and a brass rod has a diameter of 8.06 cm. If the temperature coefficient of expansion for brass is 1.9 × 10[sup]−5[/sup] (degrees C)[sup]−1[/sup] and the temperature coefficient of expansion for aluminum is 2.4 × 10[sup]−5[/sup] (degrees C)[sup]−1[/sup], to what temperature must the ring be heated so that it will just slip overthe rod?
Answer in units of degrees C.

The tire on a bicycle is filled with air to a
gauge pressure of 658 kPa at 20 degrees C.
What is the gauge pressure in the tire after
a ride on a hot day when the tire air temperature is 60 degrees C? (Assume constant volume and a
constant atmospheric pressure of 101.3 kPa.)
Answer in units of kPa.

Initially, an object has a temperature whichhas the same numerical value in degrees Celsius and degrees Fahrenheit. Then its temperature is changed so that the numerical value
of the new temperature in degrees Celsius is 5
times as small as that in Kelvin.
Find the change in the temperature (change in T =
T[sub]2[/sub] − T[sub]1[/sub]).Answer in units of K.

A force of 340 N is applied horizontally to a wooden crate in order to displace it 39.1 m across a level floor at a constant velocity. As a result of this work the crate’s internal energy is increased by an amount equal to 15 percent of the crate’s initial internal energy. Calculate the initial internal energy of the crate.
Answer in units of J.

The density of gasoline is 730 kg/m3 at 0 degrees C. One gallon of gasoline occupies 0.0038 m^3.
Gasoline’s volume expansion coefficient is 0.00096 degrees C^−1. How many extra kilograms of gasoline are obtained when fifteen gallons of gasoline are bought at 0 degrees C rather than at 18 degrees C (temperature at the filling station)? Answer in units of kg.