1. A football player pushes a tackle dummy forwards at a constant 0.85m/s for 11m using 7150J of energy. The tackling dummy mass is 120kg.
a) find force the player exerts?
b) what is the frictional force the dummy exerts?
c) what work is done by the friction as the dummy is slid along the field for 11m?
d) Is mass necessary for this question? if not, what force question could be asked that would require the mass of the dummy?
2. A person pushes a hockey puck with their stick at an angle so the vertical force is 22N [down] and the horizontal force is 45N [forward]. Assume the ice is frictionless.
a) what is the actual force the hockey plaer transmits to the puck?
b) what is the work done by the person pushing the stick if they push the puck for 3.0s as it moves with a constant velocity of 22m/s [forward]
To solve both of these physics problems, you will need to apply the basic principles of Newton's laws of motion and work-energy theorem. Let's break down each question and explain how to find the answers.
1. A football player pushes a tackle dummy forwards at a constant 0.85 m/s for 11 m using 7150 J of energy. The tackling dummy mass is 120 kg.
a) To find the force the player exerts, we can use the work-energy theorem. The work done on an object is equal to the force applied multiplied by the distance the object is moved. So, we can use the formula: work = force * distance. Rearranging the formula, we get force = work / distance. Substituting the given values, force = 7150 J / 11 m.
b) The frictional force exerted by the dummy can be assumed to be equal and opposite to the force exerted by the player since the dummy is pushed in the same direction. Therefore, the frictional force exerted by the dummy is equal to the force exerted by the player.
c) To find the work done by friction as the dummy slides along the field for 11 m, we can use the same formula: work = force * distance. Assuming the frictional force is constant along the distance, work = frictional force * distance.
d) In this question, mass is necessary to calculate the force exerted by the player and the frictional force. However, one force-related question that would require the mass of the dummy could be: "What is the acceleration experienced by the dummy?"
2. A person pushes a hockey puck with their stick at an angle so the vertical force is 22 N [down] and the horizontal force is 45 N [forward]. Assume the ice is frictionless.
a) To find the actual force the hockey player transmits to the puck, we can use vector addition. Since the vertical and horizontal forces are perpendicular to each other, we can use the Pythagorean theorem to find the magnitude of the resultant force. The actual force transmitted is equal to the magnitude of the resultant force.
b) If the puck moves with a constant velocity, it means there is no net work being done on the puck. So, the work done by the person pushing the stick is zero. Work can be calculated using the formula: work = force * distance * cos(theta), where theta is the angle between the force and displacement vectors. Since theta is 90 degrees in this case, the cosine of 90 degrees is zero, resulting in zero work.
Remember, when solving physics problems, it's important to understand the concepts and formulas involved. If you have specific numerical values, you can substitute them into the formulas to find the answers.