You do $174$ J of work while pulling your sister back on a swing, whose chain is $5\mathrm{.}10$ m

long. You start with the swing hanging vertically and pull it until the chain makes an

angle of $32\mathrm{.}0$ with the vertical with your sister is at rest. What is your sister's mass,

assuming negligible friction?

e$.$ Neither of them does any work.

$2.$ A $3\mathrm{.}00-$kg ball swings rapidly in a complete vertical circle of radius $2\mathrm{.}00$ m by a light

string that is fixed at one end. The ball moves so fast that the string is always taut and

perpendicular to the velocity of the ball. As the ball swings from its lowest point to its

highest point

a$.$ the work done on it by gravity and the work done on it by the tension in the string

are both equal to $-118$ J$.$

b$.$ the work done on it by gravity is $-118$ J and the work done on it by the tension in

the string is $+118$ J$.$

c$.$ the work done on it by gravity is $+118$ J and the work done on it by the tension in

the string is $-118$ J$.$

d$.$ the work done on it by gravity is $-118$ J and the work done on it by the tension in

the string is zero.

e$.$ the work done on it by gravity and the work done on it by the tension in the string

are both equal to zero.

$3.$ If a force always acts perpendicular to an object's direction of motion, that force cannot

change the object's kinetic energy.

a$.$ True

b$.$ False

$4.$ Two objects, one of mass m and the other of mass $2$m$,$ are dropped from the top of a

building. When they hit the ground

a$.$ both of them will have the same kinetic energy.

b$.$ the heavier one will have twice the kinetic energy of the lighter one.

c$.$ the heavier one will have four times the kinetic energy of the lighter one.

d$.$ the heavier one will have times the kinetic energy of the lighter one.