Unit 5 Lesson 2 Forces

A rock is rolling down a hill when suddenly it changes direction. What most likely caused this change?

• a decrease in friction
• an object pushing on it
• greater gravitational pull 
  
• its weight changing
  

Students in a class compare the average speeds of four toy cars rolling along the floor. The data table shows their measurements.  Which cars moved at the same speed?

• blue and green 
• orange and yellow 
• blue and orange 
• green and yellow 

Mrs. Panetta’s science class was studying motion. Four students timed a tennis ball as it rolled across the floor. The data table shows the results of their experiment.  Which students had tennis balls that rolled at the same speed?

• Alicia and Alex
  
• Alex and Lucy
  
• Lucy and Jorge
  
• Alicia and Jorge
  

Students in a class are designing a model amusement park ride. A force starts a cart moving. The cart then needs to slide along a rail and hit against a barrier. How could they prevent damage to the cart when it hits the barrier?

• Increase the acceleration of the cart as it approaches the barrier. 
• Make the rail smoother to change the amount of friction between the cart and rail. 
  
• Make the barrier out of foam so that it will absorb the force of the cart slowly.
  
• Decrease the length of the rail so that the cart has less time for its speed to increase. 

A car traveling down a road approaches a red light and stops. What causes the car’s speed to change?

• a decrease in drag
• a decrease in friction
• an increase in drag
• an increase in friction

The table shows the schedule for four busses.  If the busses follow the times on their schedules, which will have the fastest average speed along its route?

• Bus 1
• Bus 2
• Bus 3
• Bus 4

A swimmer swims across a 100-meter pool in 25 seconds. What is the swimmer’s average speed?

• 10 m/s
• 5 m/s
• 4 m/s
• 25 m/s

A boy pushes a wagon across the ground, but it moves very slowly. What change should the boy make so that the wagon moves faster?

• travel a shorter distance in the same time 
• use a greater force 
• increase the wagon's mass 
• take a longer time to travel the same distance 

During soccer practice, the manager measured the kicks of four different players. The table shows the times for the fastest kick of each player.  Which player kicked the ball with the greatest force?

• Will
• Kyle
• Corey
• Teri

Students in a class measure the speed of a toy car moving down a ramp and along a track. They know the total time for the car’s movement. What else do they need to know to find the average speed of the car?

• the mass of the car 
• the force on the car
• the direction the car moved 
• the distance the car traveled