quiz and homework

The temperature of a 100-m long aluminum bar at 30°C is increased to 90°C. The coefficient of linear expansion for aluminum is 24*10-6/°C. What is the new length of the bar?

. 100.1 m

When the skydiver reaches terminal velocity, what is her acceleration?

0

We have a bar of gold sitting on its end on the floor. The dimensions of the bar are a = .05 m, b = .09 m, and c = .02 m. What is the volume of the bar in m3?

0.000090

Calculate the contact area between the bar and the floor in m^2.

0.0010

Convert: 10 m/s into km/s

0.01

Calculate the angular (rotational) velocity.

0.099 rad/s

Convert to rpm

0.95 rpm

Convert: 100 cm into m

1 cm

In the film "2001: A Space Odyssey", a wheel like space station achieves artificial gravity by spinning around its axis. How fast should it be spinning for the people standing on the rim to feel the same gravitational acceleration as on earth? If the station had a diameter of 2 km, calculate the radius of the space station.

1 km

An object is launched at a velocity of 20 m/s in a direction making an angle of 25° upward with the horizontal. What is the total flight time of the object?

1.72 seconds

Calculate the mass of the bar in kg. The density of gold is 19,300 kg/m3.

1.737

Now, consider that when the driver hits the brake pedal, the hydraulic brake line bursts and as a result, the brakes don't work. Since the driver responds instantly to emergency situations, she decides to turn the car in a wide arc to wind up driving parallel to the wall instead of hitting it head-on (see figure). What is the centripetal force exerted on the car by turning?

10,371 N

A boy shoots an arrow at a target. The arrow has a mass of 0.08 kg. The velocity of the arrow is 50 m/s. What is the kinetic energy of the arrow?

100 J

What is the total force acting on the box? (See Homework 2 - Figures Document) 1000N <------------------> 2000N

1000N

A car is traveling 15 m/s when it begins to accelerate at a rate of 4.0 m/s2. How long will it take the car to get to a velocity of 60 m/s?

11.1

A man rides his bike 3 miles down the road to the store. If it takes him 15 minutes to get there, what was his speed in miles per hour (mph)?

12

I drop the ball off the side of the building. Half way down, at a height of 25 meters, how much potential energy does the ball have?

1470 J

A ball is launched from one end of a teeter-totter when a child jumps on the other end. If the ball's velocity is 15 m/s straight upward, what is the velocity when it hits the ground again?

15 m/s

Assuming a launch speed of 40.0 m/s and any angle between 0 and 90 degrees, what would be the largest possible range for a projectile?

163

Finally, what is the pressure being exerted on the floor by the bar of gold? (Use 9.80 m/s^2 for g)

17,022 N/m^2

The three internal angles of a triangle are a, b and, c. If you add up all of the angles, they add up to _____________________ degrees.

180

Convert: 6 meters into feet

19.6

The gravitational force due to the Earth on the moon is approximately 2.0 x 1020N. The distance between the Earth and the moon is 3.8 x 105 km. What is the gravitational force due to the moon on the Earth?

2.0 x 10^20N

When the arrow hits the target, it penetrates to a depth of 5 cm (0.05 m). What is the force that was applied by the target to stop the arrow at that depth?

2000 N

At the height of 25 meters, how much kinetic energy does the ball have?

22.1 m/s

An airplane flies at 250 mph in still air. If the plane flies into a 20 mph headwind, what is its groundspeed?

230mph

A bird flies 25 miles due west, then turns due south and flies for another 15 miles and lands. How far is the bird from its starting point?

29.1

I carry a 6 kg bowling ball to the top of a building that is 50 m high. What is the potential energy that the ball has at the top of the building?

2940 J

If one atmosphere is 101,300 N/m2, how many atmospheres of pressure would that be? .

3

I drop a brick from the top of a building. The building is 60 meters high. How long does it take to hit the ground?

3.5

A turntable spins at 33 1/3 rpm (revolutions per minute). What is that speed in radians per second?

3.5 rad/s

Calculate the acceleration due to gravity on the surface of Mars. The mass of Mars is 6.5 x 1023 kg and the radius of Mars is 3.376 x 106 m.

3.8 m/s

How much water pressure is on them at that depth? Use the results from 8. and 9. to calculate the pressure.

304,780 N/m^2

Pearl divers from Ceylon can go down to a depth of 17 fathoms without breathing gear. A fathom is a nautical measurement of depth. Convert this depth to meters. (1 fathom = 6 feet).

31.1 m

Calculate the velocity of the ball at time of impact with the ground.

31.3 m/s

From, the previous problem, how fast is the brick going when it hits the ground?

34.3

A child stands with each foot on a different scale. The left scale reads 200N and the right scale reads 150N. What is her mass in kg? The acceleration due to gravity is 9.8 m/s2.

36kg

From, the previous problem, how long does it take to fall the entire distance?

4.1

Convert: 25 mph into km/h

40.2

A car with a mass of 1200 kg is moving at 35 m/s. What is its momentum?

42,000 kg m/s

A steel cable spanning a river is 50 m long when the temperature is 25°C. What will be its length when the temperature drops to -10°C (the coefficient of thermal expansion of steel is 12 x 10-6 C-1)?

49.98m

A skydiver jumps out of a plane. Her mass is 50 kg. What is the force due to gravity (weight) of this skydiver?

490 N

When the skydiver reaches terminal velocity, what is the force due to air resistance on her?

490 N

An object is pulled northward by a force of 10 N, and at the same time another force of 15 N pulls it southward. The magnitude of the resultant force on the object is _________________.

5 N

Consider the box in the figure. What acceleration is produced when the force is applied? m = 20 kg --------> F= 100N

5 m/s^2

A driver traveling at 22 m/s slows down her 1500 kg car to a stop in order to not hit a brick wall. The distance between where she starts to brake and the wall is 75 meters. What is the average stopping force the driver experiences if she stops 5 meters before hitting the wall? (HINT- the car takes 70 meters to stop, not 75)

5,185 N

Convert: 5 m2 into cm2

50,000

A person is attracted toward the center of the Earth by a 500 N gravitational force. The Earth pushes back on the person with a force of _________.

500 N

Convert inches per minute into miles per hour.

56.5 mph

Find the linear velocity of the tire in inches per minute.

59,845 in/min

A simple pulley is used to raise a block 10 m. If 50 Joules of work are done, what was the applied force?

5N

Convert the rotational velocity of 1000 rpm into radians per minute.

6283 rad/min

The car and the truck collide head on. After the impact, they have become one and keep travelling. What is their final speed?

7.4 m/s

A child runs 5 m/s down an airport walkway that is moving at 2 m/s in the same direction. What distance does the child cover in 10 seconds?

70m

How much heat is needed to raise the temperature of 1.85 grams of copper from room temperature to its melting point?c(copper) = 386 J/kgCroom temperature = 20C melting point of copper = 1084 C

760 J

A truck with a mass of 3500 kg is moving in the opposite direction from the car at 22 m/s. What is its momentum?

77,000 kg m/s

A bowling ball falls off the top of a building and hits the ground with a velocity of 40 m/s. How high is the building?

81.6

Calculate the weight density for water.

9,800 N/m^3

A 19 inch diameter tire is rotating at 1000 rpm (revolutions per minute). The tire is attached to a car. What is the radius of the tire in?

9.5 inches

If that box has a mass of 100 kg, what is its weight here on Earth?

980 N

Substitute the values you know and calculate linear velocity on a point on the outer edge.

99 m/s

Find the correct equation for centripetal force.

Fc = mv^2/r

Find the correct equation for weight.

Fw = mg

What happens to the temperature of a confined ideal gas when the pressure is doubled while the volume is held constant?

It is doubled.

If the velocity of an object is doubled and its mass is halved, which of the following statements is true about the object?

Its momentum stays the same; its kinetic energy doubles.

Gravity has an effect on what component of velocity?

Velocity in the y-direction

What is the force required to start this box moving? 1000N <---------------> F?

anything over 1000 N

For the same triangle, according to the Pythagorean Theorem, the length of the hypotenuse is:

hypotenuse= √( adjacent 2+ opposite 2)

How does the answer to problem 2 compare to that of problem 1?

larger

According to the Pythagorean Theorem, the sine of an angle is:

opposite ÷ hypotenuse

When the distance between two charges is halved, the electrical force between the charges

quadruples

A major difference between gravitational and electrical forces is that electrical forces

repel or attract

What direction is that total force?

right

Which of the following is not a vector quantity?

time

Set these equations equal to each other and solve for the unknown quantity.

v = square root of gr