+0

# physics

0
336
1

a bicyclist was moving at a rate of 3 m/s, and then sped up to 4 m/s. If the cyclist has a mass of 100 kg, how much work was needed to increase his velocity

Guest Feb 6, 2015

#1
+19207
+5

A bicyclist was moving at a rate of 3 m/s, and then sped up to 4 m/s.

If the cyclist has a mass of 100 kg, how much work was needed to increase his velocity ?

$$\small{\text{  v_1 = 3\frac{m}{s} \qquad v_2 = 4\frac{m}{s} \qquad m = 100\ kg  }}$$

$$\\ \small{\text{  \boxed{ W=\Delta E_k=\frac12mv_2^2-\frac12mv_1^2=\frac12m (v_2^2-v_1^2)} , \qquad E_k = kinetic energy }}\\ \small{\text{ where v_1 and v_2 are the speeds of the particle before and after the work is done and m is its mass. }}\\\\ \small{\text{  \boxed { W=\frac12m (v_2^2-v_1^2)}  }}\\\\ \small{\text{ W=\frac12 *100*(4^2-3^2)\ \frac{kg*m^2}{s^2} }}\\ \small{\text{ W=50*(16-9)\ \frac{kg*m^2}{s^2} }}\\ \small{\text{ W=50*7\ \frac{kg*m^2}{s^2} }}\\ \small{\text{ W=350\ \frac{kg*m^2}{s^2} }}\\ \small{\text{ W=350\ J }}$$

heureka  Feb 6, 2015
Sort:

#1
+19207
+5

A bicyclist was moving at a rate of 3 m/s, and then sped up to 4 m/s.

If the cyclist has a mass of 100 kg, how much work was needed to increase his velocity ?

$$\small{\text{  v_1 = 3\frac{m}{s} \qquad v_2 = 4\frac{m}{s} \qquad m = 100\ kg  }}$$

$$\\ \small{\text{  \boxed{ W=\Delta E_k=\frac12mv_2^2-\frac12mv_1^2=\frac12m (v_2^2-v_1^2)} , \qquad E_k = kinetic energy }}\\ \small{\text{ where v_1 and v_2 are the speeds of the particle before and after the work is done and m is its mass. }}\\\\ \small{\text{  \boxed { W=\frac12m (v_2^2-v_1^2)}  }}\\\\ \small{\text{ W=\frac12 *100*(4^2-3^2)\ \frac{kg*m^2}{s^2} }}\\ \small{\text{ W=50*(16-9)\ \frac{kg*m^2}{s^2} }}\\ \small{\text{ W=50*7\ \frac{kg*m^2}{s^2} }}\\ \small{\text{ W=350\ \frac{kg*m^2}{s^2} }}\\ \small{\text{ W=350\ J }}$$

heureka  Feb 6, 2015

### 31 Online Users

We use cookies to personalise content and ads, to provide social media features and to analyse our traffic. We also share information about your use of our site with our social media, advertising and analytics partners.  See details