Physics Answers

Bailey is on the tenth frame of her recent bowling competition and she needs to pick up the last pin for a spare and the first place trophy. She rolls the 7.39 kg ball down the lane and it hits the 1.41 kg pin head on. The ball was moving at 7.9 m/s before the collision. The pin went flying forward at 1.7 m/s. Determine the post-collision speed of the ball.

An 108.0 kg boy and a 61.1 kg girl, both wearing skates face each other at rest on a skating rink. The boy and girl push each other, sending her eastward with a speed of 3.09 m/s. Determine the final velocity of the boy. Neglect friction.

A bicycle has a momentum of 24 kg m/s. What momentum would the bicycle have if it had…

… twice the mass and was moving at the same speed?

Answer 1

… the same mass and was moving with one-half the speed?

Answer 2

… three times the mass and was moving with twice the speed?

Answer 3

… one-half the mass and was moving with twice the speed?

Answer 4

… the same mass and was moving with twice the speed?

Answer 5

… three times the mass and was moving with one-half the speed?

When the blender is empty and running at high speed, how much time is required for a blade to turn by 90 degrees

A child throws a 0.50 kg snowball at his friend at 12.0 m/s but the snowball lands on the ground in front of his friend.

The snowball is 1.3 m above the ground when it leaves the child’s hand.

(a) What is the (i) kinetic energy & (ii) potential energy of the snowball at the time of release?

(b) What is the total energy of the snowball (i) at the time of release & (ii) just before it hits the ground?

(c) What is the snowball’s kinetic energy just before it hits the ground in front of his friend?

(d) How fast is the snowball moving just before it hits the ground in front of his friend?

A toboggan carrying two children (total mass = 85 kg) reaches its maximum speed at the bottom of a hill, and then glides to a stop in 21 m along a horizontal surface.The coefficient of kinetic friction between the toboggan and the snowy surface is 0.11.

(a) Draw a FBD of the toboggan as it slows down, and calculate the magnitude of ALL the forces in the diagram.

(b) Calculate the acceleration of the toboggan.

(c) Calculate the work done on the toboggan by the friction on the snowy surface.Should the work be positive or negative?Explain.

10. A pulley system operated with an electric motor consumes 5.0 kJ of energy as it does 3.2 kJ of work in raising an object. The efficiency of this technology is:

(a) 64% (b) 84%

(c) 119% (d) 156%

8. Consider an object falling from a height of 300 m. If we ignore air resistance, its total energy:

(a) increases during the fall.

(b) decreases during the fall.

(c) remains constant during the fall.

(d) is zero at the start of the fall.

7. In which of the following is gravitational potential energy being transformed into kinetic energy?

(a) A car accelerating on a level road.

(b) A raindrop falling freely through the air.

(c) Water turning an electric turbine.

(d) A stone thrown up into the air.

6. If the mass of an object is quadrupled and the speed decreased by a factor of three, by what factor does the kinetic energy change?

(a) 4/3 (b) 16/3

(c) 4/9 (d) 16/9