Recent content by monkfishkev

Homework Statement The driver of a truck moving at 30m/s suddenly notices a moose 70m straight ahead. If the driver's reaction time is 0.5s and the maximum deceleration is 8m/s^2, can he avoid hitting the moose without steering to one side? The Attempt at a Solution First I found out how...

OK I've tried it a second time and come out with a different answer. I differentiate x = 4t^2 - t^3 to become v = 8t - 3t^2 Making v = 0 I get either v = 2.6 or v = 0. How do I know which one to use. I then differentiate further to solve for acceleration. a = 8 - 6t when making a = 0 I get...

Homework Statement An object starts from position X = 0 and moves along a straight line with its position given by x = 4t^2 - t^3 where t is the time taken to reach position x. Find: i) The time at which the velocity is zero ii) The time at which the acceleration is zero iii) The average...

Homework Statement A car moving at 60km/h meets a train of length 1km moving at 40km/h along a track parallel to the road. What distance does the car travel in passing the length of the train given that they travel a) in the same direction, or b) in opposite directions? Homework Equations...

should they be the same?

thank you

I think I get it now. Are the answers; t = 3s and s = 39m

Suvat -- Two cars approach each other on a straight road Homework Statement Two cars approach each other on a straight road. Car A is moving at 16m/s and car B at 8m/s. When they are 45m apart both drivers apply their brakes. Car A slows down at a rate of 2m/s^2 while car B slows down at...

I must be doing this wrong: v = 20 - 15t^2 After 1s, v = 20 - 15(1) = 5m/s After 2s, v = 20 - 15(4) = -40m/s After 3s, v = 20 - 15(9) = -115m/s Average speed = 5 - 40 - 115 = = -150 ÷ 3 = -50m/s

Can you please explain how you come to get -25. Thanks for your time :-)

An object starts from position X = 0 and moves along a straight line with its position given by; X = 20t - 5t^3 where t is the time taken to reach position X. Find; i) The time at which the velocity is zero ii) The time at which the acceleration is zero iii) The average velocity over the...