● Use lubricants such as oil.
● Place the load on a piece of cloth as it can ease the friction
● Place the load on a cart with wheels so it can be converted to rolling friction and can be pushed easily.
● Place the load on an inclined plane

3 0

3 years ago

Derek and Diane race each other on bicycles. Derek starts 4 seconds before Diane. He goes at a steady speed of 6 m/s. Diane star

ser-zykov [4K]

a. $x(t) = vt' = v(t+4) = 6(t+4) [m]$

Let's call:

$t$ the time calculated from the moment Diane starts her motion and $t'$ the time calculated from the moment Derek starts his motion. Derek starts his motion 4 seconds before Diane: this means that has an "advantage" of 4 seconds, so we can write

$t'=t+4$

Then:

$v=6 m/s$ is the uniform speed of Derek

Derek is moving in a uniform motion, so Derek's position will be given by (assuming that the starting position is zero):

$x(t) = vt' = v(t+4) = 6(t+4) [m]$

We see that this is correct: in fact, when t=0 (instant when Diane starts her motion), Derek has already travelled for

$x(t=0)=v(0+4)=6 (4)=24 m$

b. $x'(t)= \frac{1}{2}at^2 =\frac{1}{2}(2)t^2=t^2 [m]$

t is the time calculated from the moment Diane starts her motion. Diane is moving by accelerated motion, with constant acceleration $a=2 m/s^2$ and initial velocity $v_0=0$ , so its position at time t is given by the law of uniform accelerated motion: