Transcript PowerPoint used in class today

FORCES AND
NEWTON’S LAWS
Practice Problems
Send the tallest person in your group to grab whiteboard
and marker box
Make sure you have at least 2 people at your table group!
#1
• A Saturn V rocket has a mass of 2.75 x 106 kg and exerts
a force of 3.30 x 107 N on the gases it expels.
• A. What is the net force acting on the rocket upon liftoff?
• B. What is the initial vertical acceleration of the rocket?
#2
• Anna is pushing Olaf on a sled across a flat, snow-
covered patio. The coefficient of static friction between
the sled and the snow is 0.12. The coefficient of kinetic
friction between the sled and the snow is 0.10. Olaf has a
mass of 12.5 kg, and Anna is pushing down on the sled
with a force of 55 N at an angle of 30.0° from the
horizontal.
• Will Olaf and his sled begin to move?
• With what force must Anna push Olaf once he’s moving in order to
keep him moving with a constant velocity?
#3
• Sally, m = 45.0 kg, is sitting on a sled that has a mass of
3.5 kg. The coefficient of static friction between the sled
and the snow is 0.12. If Linus is pulling at an angle of
35.0° to the horizontal, what force would he need to apply
in order to start Sally and her sled moving?
• If Linus keeps pulling with that same force, what is the
acceleration of Sally and her sled? Assume the coefficient
of kinetic friction is 0.08.
#4
• A skier has just begun sliding down a 30.0° incline.
Assume the coefficient of kinetic friction between her skis
and the snow is 0.090. What is her final velocity after
skiing for 4.0 s?
#5
• An Olympic skier coasts down a slope with an angle of
inclination of 37°.(a) Neglecting friction, how many
forces act on the skier?
•
(b) What is the acceleration of the skier?
•
(c) If the skier has a speed of 5 m/s at the top of the
slope, what is his speed when he reaches the bottom
of the 35 m long slope?