 # Speed.

## Presentation on theme: "Speed."— Presentation transcript:

Speed

What is time? A particular moment An interval of time
10:25 and 15 secs An interval of time 7pm to 7am

Time Measured in hours, minutes, days, years and seconds
Metric only in science Always a number and a unit secs

What is distance? How far from one point to another Unit of length
Metric only in science Always a number and a unit – 25 m

Speed Measure of how quickly an object moves from one place to another
An object that is not moving has a speed of zero m/s Distance traveled divided by the time taken 90 miles in 1.5 hours = 90mi /1.5 h = 60 mph

Velocity Speed of the object and the direction of its motion

Speed Speed = v v is for velocity (speed with direction added, traveled 75 mph south) Distance = d Time = t

Problems A nascar driver has a car that is one of the fastest on the circuit. If it travels 600 miles in 4 hours, what is his cruising speed? v = d/t v = ? d = 600 miles t = 4 hrs 3. v = 600 mi/4 hrs 4. v = 150 mi/hr

The fastest car on Earth, a German-made Thrust SSC, would win every Nascar race in America. If it takes 0.5 hours (30 minutes) to travel 380 miles, what is its speed? v = d/t v = ? d = 380 miles t = 0.5 hrs 3. v = 380 mi/ 0.5 hr 4. v = 760 mi/h (mph)

The fastest train on Earth, the TGV from France, can travel at faster speeds than trains in the United States. During a speed test, the train traveled 800 miles in 2.5 hours. What is its speed? v = d/t v = ? d = 800 miles t = 2.5 hrs 3. v = 800 mi/ 2.5 hr 4. v = 320 mi/h (mph)

Spirit of Australia, a hydroplane boat, made speed records by traveling 239 miles in 0.75
hours (45 minutes). What is its record-breaking speed? v = d/t v =? d =239 miles t = 0.75 hrs 3. v = 239 mi/ 0.75 hr 4. v = mi/h (mph)

How much time does it take for a bird flying at a speed of 45 miles per hour to travel a distance of 1,800 miles? t = d/v t = ? d = 1800 miles v = 45 mph 3. t = 1800 mi /45 mi/hr 4. v = 40 hrs

A cheetah runs at 60 mph for a distance of 0. 5 miles
A cheetah runs at 60 mph for a distance of 0.5 miles. How long does this take? Change answer to seconds. t = d/v t = ? d = 0.5 miles v = 60 mph 3. t = 0.5 mi/ 60mph 4. t = hr 0.008 hr x 60 min X 60 sec = secs 1hr 1 min

A comet is cruising through the solar system at a speed of 50,000 kilometers per hour for 4 hours time. What is the total distance traveled by the comet during this time? d = vt d = ? v = 50,000 km/h t = 4 hrs 3. d = 50,000 km/h X 4 hrs 4. d = 200,000 km

d = 372.6 mph/min (Does this make sense) Must change minutes to hours
A runner runs 6.9 mph for 54 minutes. What distance did the runner travel? d = vt d = ? v = 6.9 mph t = 54 minutes 3. d = 6.9 mph X 54 min d = mph/min (Does this make sense) Must change minutes to hours 54 min X 1 hour = 0.9 hr 60 min d = 6.9 mph X 0.9 hr = 6.2 miles

Time vs distance Graph Shows distance traveled in relation to time traveled Line sloping upward – steady speed Change in upward slope = changing speed Steeper = faster Flat line – no motion Downward slope – returning to start

Time vs distance Graph Slope of a distance/ time graph or a position/time graph will tell us the speed Slope = rise/run Slope = 60 miles/2 hrs Speed = 30 miles/hr

Average Speed Average of all speeds over time traveled
Speed may not be constant Distance to San Antonio, Texas 1000 miles Time traveled 15 hours Average speed equals 66.66 mph

Instantaneous Speed Speed at a certain moment in time