Question

Assume that g is 10 N/kg and that air resistance and other

frictional forces are negligible.
1 )An object has a mass of 6 kg What is its gravitational potential energy
a( 4 m above the ground
b) 6 m above the ground?

2) An object of mass 6 kg has a speed of 5 m/s.
a What is its kinetic energy?
b What is its kinetic energy if its speed is doubled?


3 A ball of mass 0.5 kg has 100 J of kinetic energy. What
is the speed of the ball?

help with this its very important plss​

Answer 1

1) Given acceleration due to gravity as 10N/kg

N/kg is the same as m/s². From W=mg

making g subject ... you have g = W/m

where m is in kg and W is in N

hence we have N/kg

So g=10ms-²

Gravitational Potential Energy=mgh

At height 4m

PE=6 x 10 x 4

=240J.

At height 6m

PE=6 x 10 x 6

=360J.

2) KE=1/2mv²

=1/2 x 6 x 5² =75J

When the speed is doubled... it becomes 2x

so V = 2x5=10ms-¹

KE=1/2 x 6 x 10² =300J.

3) KE=1/2mv²

KE is given as 100J

mass=0.5kg

Making V the subject

you have v² =2KE/m

v²=2 x 100/0.5

v²=400

taking square root

v=20ms-¹.

Have a great day✌