Mechanics | Relativity Answers

Sally travels by car from one city to another. She drives for 28.0 min at 60.0 km/h, 38.0 min at 31.0 km/h, and 22.0 min at 35.0 km/h, and she spends 14.0 min eating lunch and buying gas.
(a) Determine the average speed for the trip.

(b) Determine the total distance traveled.

a 6kg cart on a level surgacr is pulled at a constant velocity of 2m/s by a constant force of 10 N. What is the acceleration ? What is the friction force opposing the motion?

a 1600-kg car is traveling at 20 m/s around a curve with a radius of 120m. What is the angular momentum of the car?

A spaceship moving with an initial velocity of 58.0 meters/second experiences a uniform acceleration and attains a final velocity of 153 meters/second. What distance has the spaceship covered after 12.0 seconds?

A.

6.96 × 102 meters




B.
1.27 × 103 meters




C.
5.70 × 102 meters




D.
1.26 × 102 meters




E.
6.28 × 102 meters

A ball rolls off the top of stair way with a horizontal velocity of magnitude 2 m/s.The steps are 10 cm high and 20 cm wide. if g =10 m/s^2 ,then the ball hits first the edge of which step?

represent the given velocity 230km/h in the direction 2000

A ranger in a national park is driving at 28.0 mi/h when a deer jumps into the road 155 ft ahead of the vehicle. After a reaction time t, the ranger applies the brakes to produce an acceleration of a = -9.00 ft/s2. What is the maximum reaction time allowed if she is to avoid hitting the deer?

An indestructible bullet 2.00 cm long is fired straight through a board that is 10.0 cm thick. The bullet strikes the board with a speed of 460 m/s and emerges with a speed of 300 m/s. (To simplify, assume that the bullet accelerates only while the front tip is in contact with the wood.)

a) what is the average acceleration of the bullet through the board? answer m/s^2
b) What is is the total time that the bullet is in contact with the board? answer s
c)What thickness of board (calculated to 0.1 cm) would it take to stop the bullet, assuming that the acceleration through all boards is the same? answer cm

Consider a double star system under the influence of the gravitational force between the stars. Star 1 has mass m1 = 1.42 × 1031 kg and Star 2 has mass m2 = 2.62 × 1031 kg. Assume that each star undergoes uniform circular motion about the center of mass of the system (cm). In the figure below r1 is the distance between Star 1 and cm, and r2 is the distance between Star 2 and cm.
If the stars are always a fixed distance s=r1+r2 = 3.48 × 1018 m apart, what is the period of the orbit (in s)?

A bead of mass m slides without friction on a vertical hoop of radius R . The bead moves under the combined action of gravity and a spring, with spring constant k , attached to the bottom of the hoop. Assume that the equilibrium (relaxed) length of the spring is R. The bead is released from rest at θ = 0 with a non-zero but negligible speed to the right.
(a) What is the speed v of the bead when θ = 90∘ ? Express your answer in terms of m, R, k, and g.
(b) What is the magnitude of the force the hoop exerts on the bead when θ = 90∘ ? Express your answer in terms of m, R, k, and g.