Question

A 520kg rocket sled at rest is propelled along the ice by an engine developing a constant thrust of 12 000 N over a distance of 40 m. Assuming all of the work goes into motion, calculate a). The work done by the engine on the sled after 40 m b). Its velocity after 40 m (using the kinetic energy formula).​

Answer 1

Answer:

a) 480 000 J

b) 43 m/s

Explanation:

a)

To calculate the work done by the engine, we can use the following formula:

$\boxed{\mathrm{Work \space\ done = Force \times Distance}}$.

                  ⇒ $12000 \times 40$

                  ⇒ $480000 \space\ \mathrm J$

b)

We know that the work done by the propeller was converted into motion of the sled, which means the propeller provided the sled with kinetic energy.

∴ work done by propeller = kinetic energy gained by sled

⇒ $480000 = \frac{1}{2} mv^2$

⇒ $480000 = \frac{1}{2} \times 520 \times v^2$

⇒ $480000 = 260v^2$

⇒ $v^2 = \frac{480000}{260}$

⇒ $v =\bf 43 \space\ m/s$

This means that its velocity after 40 m was 43 m/s.