1. PE = mg*h = 15 *9.8*0.5 = 73.5 J.
2. 0.5*0.25*V^2 = 15
0.125V^2 = 15
V^2 = 120
V = 11 m/s.
3. KE1 = 0.5m*V^2
KE2 = 0.5*(0.5m)*(3V)^2 = 0.5*0.5m*9V^2 = 0.25m*9V^2 = 2.25m*V^2.
KE2/KE1 = 2.25m*V^2/0.5m*V^2=4.5 = 9/2.
4. You didn't show the choices. However,
PE = mg*h. Therefore. PE increases with
height.
6. a = (V^2-Vo^2)/2d = (10^2-0)/1.5 =
66.67 m/s^2.
F = m*a = 0.5 * 66.67 = 33.33 N.
1. A 15 kg boy falls out of his bed at a height of 0.50 m. What is the amount of gravitational potential energy lost by the boy?
my answer: 74 J
2. What is the speed of a 0.25 kg ball if its kinetic energy is 15 J?
my answer: 11 m/s
3. if the speed of an object is tripled and the mass is halved by what factor does the kinetic energy change?
my answer: 9/2
4. a ball is thrown up in the air. Which of the following quantities increases as the ball gets higher?
my answer: gravitational potential energy
5. a 10.0 kg crate slides across the floor 13 m against a force of friction of 7.5 N. what is the thermal energy produced?
my answer: 98 J
6. in the process of being thrown, a 500.0 g ball goes from rest to a speed of 10.0 m/s over a distance of 0.75 m. What is the force that was exerted on the ball?
my answer 33N
2 answers
12
3 answers