The space shuttle design team spent two years working with sketches and models before building the shuttle. Why were these steps important? 1.Sketches and models allowed for the design to be modified before investing huge amounts of time and money to build the actual shuttle.

2.Sketches and models allowed for many different astronauts to provide input on the design of the shuttle before investing money in the actual shuttle.

3.Sketches and models helped astronauts in their training program as they prepared for their missions.

In which situation has the independent variable for the experiment been changed? check all that apply. changed from counting the number of duckweed at day 0 and day 14 to counting them every day changed from testing duckweed growth in beakers to testing duckweed growth in large outdoor tanks changed from testing the effect of ph on duckweed growth to testing the effect of light levels on duckweed growth changed from testing the effect of acid ph on duckweed growth to testing the effect of basic ph on duckweed growth

1.what is where an object is located 2. what is how fast an objects speed is changing 3. what is how fast an object is moving

As part of your daily workout, you lie on your back and push with your feet against a platform attached to two stiff springs arranged side by side so that they are parallel to each other. when you push the platform, you compress the springs. you do an amount of work of 79.0 j when you compress the springs a distance of 0.230 m from their uncompressed length. (a) what magnitude of force must you apply to hold the platform in this position? (b)how much additional work must you do to move the platform a distance 0.230 m farther? (c) what maximum force must you apply to move the platform a distance 0.230 m farther?