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Lesson: Normal Reaction Force

Worksheet: Normal Reaction Force • 4 Questions


A roller coaster car starts to move from rest at the top of a track that is 30.0 m long and inclined at an angle below the horizontal. Assume that friction is negligible.

What is the magnitude of the acceleration of the car?

How much time passes before the car reaches the bottom of the track?


A 120-kg astronaut is riding in a rocket sled that is sliding along an inclined plane. The sled has a horizontal component of acceleration of 5.0 m/s2 and a downward component of 3.8 m/s2. Calculate the magnitude of the force on the rider by the sled. (Hint: Remember that gravitational acceleration must be considered.)


A student’s backpack, full of textbooks, is hung from a spring scale attached to the ceiling of an elevator. When the elevator is accelerating downward at 3.8 m/s2, the scale reads 60 N.

What is the mass of the backpack?

What does the scale read if the elevator moves upward while slowing down at a rate 3.8 m/s2?

What does the scale read if the elevator moves upward at constant velocity?

If the elevator had no brakes and the cable supporting it were to break loose so that the elevator could fall freely, what would the spring scale read?


A block of mass 2.0 kg is on a perfectly smooth ramp that makes an angle of below the horizontal.

What is the magnitude of the block’s acceleration down the ramp?

What is the magnitude of the force of the ramp on the block?

What magnitude force applied upward along and parallel to the ramp would allow the block to move with constant velocity?