Energy Problems II - Energy | Show Me The Physics

Name the energy conversion that occurs in a Grandfather clock.

School blocks YouTube? GrandfatherClock.mp4

Video Instruction

Ex 2

Given

A 10 kg frictionless cart is resting on a horizontal table. A force of 10 N is applied for a distance of 8 m. What is the cart’s new kinetic energy?

m = 10 kg · F = 10 N · d = 8 m

KE = ½mv² ??

↓

ΔKE = W = Fd = 10 N × 8 m

= 80 N·m

Ex 3

Given

100 joules of work is needed to lift a 100 kg object from the ground.
What is the object’s new P.E.?

↓

W = ΔPE = 100 J

Ex 4

Given

Crate is pulled 6.00 m up an incline with a force of 50.0 N. PE of the cart increases by 250. J. What is the total work done against friction?

d = 6.00 m · F = 50.0 N · ΔPE = 250. J

↓

W = Fd = 50.0 N × 6 m = 300. J

W = ΔPE + W_f

300. J = 250. J + W_f

W_f = 50.0 J

Ex 5

Given

4 N is exerted on a 1 kg mass at rest for 2 m, causing it to move.

A. Find the object’s KE.

KE = ½mv²

Work on object = ΔKE

ΔKE = W = Fd = 4 N × 2 m

= 8 N·m

B.

Find the object’s velocity.

↓

KE = ½mv²

8 N·m = ½(1 kg)(v²)

16 = v²

v = 4 m/s

Ex 6

Given

A force of 100.0 N lifts the object 10.00 m off the ground. What is the object’s new potential energy? What is the mass of the object?

↓

ΔPE = W = Fd = 100.0 N × 10.00 m

= 1000. N·m

PE = 1000. J = mgh

m(9.8 m/s²)(10.00 m) = 1000. J

m = 10.20 kg