Hey everyone,(adsbygoogle = window.adsbygoogle || []).push({});

Just wondering if anyone could help me with my physics homework. It's my first time ever doing physics and I was always terrible at maths. It needs to be in soon so I'm kind of freaking out If anyone could either show me how to answer these questions or even pm I'd be very grateful.

1. [a] The radius of a circle is 2mm. Write down an expression for its area A in scientific notation of the form A = a x 10 to the power of -b m to the power of -2, where a and b are constants.

A sphere of lead has a mass of 0.1 kg. If the density of lead is 11.3 x 10 to the power of 3 kg m to the power of -3, find the radius of the sphere [remembering that density = mass over volume]

2. [a] What is the speed in kilometres per second of a car travelling at a constant speed of 60 miles hr to the power of minus 1? [1 mile = 1.609 km]

What is the speed of the car in metres per second? [1km = 10 to the power of 3 m]

[c] What is the average speed for a trip of 157 km that requires 2.45 hr?

[d] How far in km will a car go in 3.5 hr at a constant speed of 95 km hr to the power of -1?

I know this might seem really easy to people who are into physics but to me this is really hard.

**Physics Forums | Science Articles, Homework Help, Discussion**

Dismiss Notice

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Need Help

**Physics Forums | Science Articles, Homework Help, Discussion**