Physics 1 questions i need help to figure out how to solve these 5 ?'s any help would be appreciated?

Question

4. for an automobile speedometer what would be the equivalent scale readings in kilometers per hour for : 10 , 20 , 30, 40, 50, 60, 70, 80, 90, 100 mi/hr?

5. A typical wide reciever in american football can run the 40-yd dash in about 4.5 seconds starting from rest (A) what is his average spped in m/s? what is his average speed in mi/hour.. please show work

6. what is the smallest division of measurement on a meter stick?

7. If you are going thre a tunnel that is 31 miles long with an average speed of 75 mi/ hour, how long in minutes would it take to make a one-way trip threw the tunnel?

8. A student doing a lab experiment drops a small solid cube into a cylindrical glass of water. the inner diameter of the glass is 6.00cm. the cube sinks to the bottom, and the water level in the glass rises 1.00cm. If the mass of the cube is 73.6g (A) determine the length of one side of the cube. (B) calculate the cubes density. (work the exercise in cgs units for convenience.)

any help with any of these would be grealty appreciated... thank you sooooo much!!!!

Answer 1

4. to change kilometers/hour to miles/hour you simply use the following conversions.

1 kilometer is equal to 0.6214 miles.

So, you have (10 km/h)*(0.6214 miles/1 km).  All you have to do is change the kilometer/hour value and do the same for all of the number in problem 4.

5. Average speed is distance traveled/time elapsed.  so for part a) first convert 40 yards to meters to do this you take

40 yards*(3 feet/1 yard)*(1 meter/3.281 ft)=36.57 m

so the average speed is then (0m+36.57m)/(0s+4.5s)=8.127 m/s

b) convert yards to miles

(40 yards)*(3 feet/1yard)*(1 mile/5280 feet)=0.0227 miles

convert 4.5s to hours

4.5 s*(1 min/60 s)*(1 h/60 min)=0.00125 hours

Average speed=(0+0.0227 miles)/(0s+0.00125)=18.16 mi/h

6) millimeters

7)  First change mi/h to mi/min

(75mi/h)*(1h/60 min)=1.25 mi/min

average speed=distance traveled/time elapsed

1.25 mi/min=31miles/time

(1.25 mi/min)(time)=31 mi

time=(31 mi)/(1.25mi/min)

time=24.8 min

8) Density=mass/volume

Volume of a cube= length*width*height

Volume of a cylinder=pi*radius^2*height

for this problem you will also have to convert your units to the proper units

Answer 2

Julie,

These are mostly conversion questions which are solvable using ratios.

You should do what you can first: find the conversion for miles to kilometres, yards to metres and miles. Then post again.

Also, speed equals distance divided by time, so TIme=distance divided by speed, and density=mass/volume.

Good luck.