A child’s toy launches a model parachutist of mass 0.40 kg vertically upwards. The model parachutist reaches a maximum height of 8.5 m. Calculate a) the gravitational potential energy gained by the model parachutes, b) the minimum possible speed with which the model parachutist was launched. c) In practice, the launch speed must be greater than the value calculated in (b). Explain why? *

(a) =34.0J

(b) = 13.038m/s

(c) =

Explanation:

(a) mass (m) =0.45kg

Height(h) =8.5m

Gravity (g) =10m/s^2

But P. E (Potential Energy) = mass × gravity× height

P. E = 0.45×10×8.5

P. E = 34.0J

(b) using v^2=u^2 - 2gs

Where v = final velocity

u= initial velocity

g = gravity

s =distance

But at maximum height v =0

0^2= u^2 - 2gs

Transpose u^2 we have

u^2 = 2gs

u^2 = 2×10×8.5

u^2 = 170

u = square root of 170

u = 13.038m/s

5 w for 1hr = 5x60x60 joules=300x60=3000x6=18,000j as total energy conversion. efficiency of bulb needed for radiant to thermal within 18000

f=ma newton's second law 7x8=56n