Mechanics | Relativity Answers

Consider a spherical shell planet that is to be built from solid iron, with density 7.9 x 103 kg/m[sup]3[/sup]. The thickness, t, of the shell is the difference between the inner and outer radius, t = R - a.1. Show that if t << a, then the value of g is directly proportional to t and independent of the radii values.
2.What is t for g = 10 m/s[sup]2[/sup]? (The answer to this last question will give an idea of how large R and a must be for this approximation to be valid.)

An elevator starts from rest with a constant
upward acceleration and moves 1m in the first
1.5 s. A passenger in the elevator is holding a
9.6 kg bundle at the end of a vertical cord.
The acceleration of gravity is 9.8 m/s2 .
What is the tension in the cord as the ele-
vator accelerates?
Answer in units of N.

The distance between two telephone poles is
49 m. When a 1.35 kg bird lands on the
telephone wire midway between the poles, the
wire sags 0.185 m.
The acceleration of gravity is 9.8 m/s2 .
How much tension in the wire does the bird
produce? Ignore the weight of the wire.
Answer in units of N.

A shopper in a supermarket pushes a cart
with a force of 38 N directed at an angle of
26.4◦ downward from the horizontal.
Find the work done by the shopper as she
moves down a 49.2 m length of aisle.
Answer in units of kJ.

A rain cloud contains 3.36 × 107 kg of water
vapor.
The acceleration of gravity is 9.8 m/s2 .
How long would it take for a 3.6 kW pump
to lift the same amount of water to an altitude
of 17000 m?
Answer in units of years.

In an automobile race, the cars are started with a starter car traveling at 31.5 m/sec. If the lead car has an average acceleration of 4.3 m/sec^2 during the first 3 seconds, how fast was it traveling at the end of 3 seconds and how far did it go?

A bob sled race (down a straight course) is able to enter the starting gate with a speed of 4.0 m/sec and the average acceleration down the hill was 6.2 m/sec^2. If the sled covers the course in 1.35 seconds, how fast was it moving at the bottom of the course?

A woman driving a car traveling 30 m/sec spots a board in the road. The reaction time of the woman is 0.20 seconds and the car can brake with a deceleration of 4.0 m/sec^2. How far does the car travel before the brakes are applies? What is the total stopping distance from the time she spotted the board? (hint: The total distance is the distance before she applies the brakes afterwards.)

A ball slowly rolls off a 1 meter high table and falls straight down. How long does it take for the ball to hit the florr and how fast will it be going just before it hits the floor? The acceleration of the ball due to gravity is 9.81 m/sec^2?


can you give answer, than show work?

If a car starts from rest and accelerates at 5.0 m/sec^2 for 6.0 seconds, how far did it travel and how fast was it moving at the end of the 6.0 seconds?



Can you show work please?