# Pysics 11 problem. help please?

## Homework Statement

Pam has a mass of 40.0kg and she is at rest on a smooth level frictionless ice. pam straps on a rocket pack. the rocket pack supplies a constant force for 22.0m and pam acquires a speed of 62.0m/s

a)what is the magnitude of the force?
b)what is pams final kinetic energy

a)F=mg
b)Ek=1/2mv^2

## The Attempt at a Solution

a)
m=40.0kg
d=22.0m
v=62.0m/s
F=mg
F=(40.0)(9.8)
F=392N

b)
m=40.0
v=62.0
Ek=?
Ek=1/2mv^2
Ek=1/2(40.0)(62.0^2)
Ek=7.69x10^4J

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cristo
Staff Emeritus

## Homework Statement

Pam has a mass of 40.0kg and she is at rest on a smooth level frictionless ice. pam straps on a rocket pack. the rocket pack supplies a constant force for 22.0m and pam acquires a speed of 62.0m/s

a)what is the magnitude of the force?
b)what is pams final kinetic energy

a)F=mg
b)Ek=1/2mv^2

## The Attempt at a Solution

a)
m=40.0kg
d=22.0m
v=62.0m/s
F=mg
F=(40.0)(9.8)
F=392N
This is not the force you were asked for: this is the weight of the person. Try using the relevant kinematic equation to calculate the acceleration, then use newtons 2nd law to work out the force.
b)
m=40.0
v=62.0
Ek=?
Ek=1/2mv^2
Ek=1/2(40.0)(62.0^2)
Ek=7.69x10^4J
This looks fine

how do i figure out the acceleration without the force?

wow i definately did not do this right, i got 3480

cristo
Staff Emeritus
how do i figure out the acceleration without the force?
Using the kinematic equations [hint: the relevant one to use here is v2=u2+2as, where here v is the final velocity, u is the initial velocity, a is acceleration and s is the distance.]

cristo
Staff Emeritus
wow i definately did not do this right, i got 3480
I get 3495N

i got 3520

ok so if you put it into sig figs you would get 3.5x10^3

cristo
Staff Emeritus
ok so if you put it into sig figs you would get 3.5x10^3
Yes, if you're using 2sf.

ok so thats right then?