Anonymous
Anonymous asked in Science & MathematicsPhysics · 1 month ago

# gr 12 physics?

A 31.0 kg child on a swing reaches a maximum height of 1.92 m above their rest position. Assuming no loss of energy:

a) At what point during the swing will she attain their maximum speed?

b) What will be her maximum speed through the subsequent swing?

c) Assuming this maximum height was the result of one push from her parent, what was the average force exerted by the parent if they pushed over a distance of 152 cm?

Relevance

When the potential energy is a minimum the kinetic energy is a maximum. ie at the bottom of the swing.

b) Ek = Ep -> 1/2 m v^2 = mgh-> v= sqrt( 2h*g) = sqrt( 2*1.92*9.8) m/s

c) E = F.d -> mgh = F.d -> F = mgh/d= 31*9.8*1.92/1.52 N

• Andrew Smith
Lv 7
1 month agoReport

thanks .. put in a division when it should have been a multiplication.  fixed now.

• Login to reply the answers
• Conservation of Energy

When swing is at the lowest, the PE has become KE

mgh = 1/2 m v^2

So v = √(2gh)  so plug in numbers and solve, round to 3 sigfigs

6.14 m/s

• Login to reply the answers
• Anonymous
1 month ago

a)

at the lowest point of the swing

b)

V = √2gh = √19.612*1.92 = 6.14 m/sec

c)

m*g*h = F*d

F = 31*9.806*1.92/1.52 = 384 N

• Login to reply the answers
• Anonymous
1 month ago

On Earth,  or the International Space Station, or on the Moon?

• Raymond1 month agoReport

its probably on earth but idk this guy shouldve been specific

• Login to reply the answers