Physics Problem Set

A child is sledding down a hill that makes an angle of 38° with the horizontal x axis. The mass of the child and sled is 30kg. If the coefficient of friction between the sled runners and the snow is 0.099, calculate the downhill acceleration. Drawing a FBD would be helpful.

Answer explanation

Tags

NGSS.HS-PS2-1

A box has a mass of 18.0kg and sits on a surface which gives a coefficient of sliding friction of 0.117. What force must be applied to the box to give it an acceleration of 4.31 m/s²? Drawing a FBD would be helpful.

Answer explanation

m = 18kg

μ = 0.117

ΣF = ma -> F_A-F_f = ma -> F_A = F_f + ma

F_f = μF_n -> F_f = μmg

F_A = μmg + ma

= (0.117)(18)(9.8) + 18(4.31)

= 98.2N

Tags

NGSS.HS-PS2-1

A car has a mass of 1825kg wishes to park on a snowy hill that makes an angle 21.2° with the horizontal. The coefficient of the friction between the tires and the hill is 0.182. Will the car be able to park on the hillside?

Answer explanation

m = 1825 kg

μ = 0.182

F_II = mgsinθ

= (1825)(9.8)*sin(21.2°)

=6467.7 N

F_f = μmgcosθ

=(0.182)(1825)(9.8)*cos(21.2°)

=3034.8 N

No. The car will not be able to park. The force of friction is less than the parallel force. Therefore, there's not enough traction to get the car to move.

Tags

NGSS.HS-PS2-1

A skier is on a slope that makes an angle of 39.2° from the horizontal. If the coefficient of friction between the skis and the snow is 0.088, what is the maximum downhill acceleration possible if we ignore air resistance. Drawing a FBD would be helpful.

Answer explanation

Tags

NGSS.HS-PS2-1

A person swims east a 3.5 m/s while a river flows south at 5.0 m/s. If the river is 35 meters wide, how long will it take to swim across?

Answer explanation

Two forces are 1250 N @ 23° and 1153 N @ 115°. What is the value of the resultant? Type out the word "degrees" when applicable.

Answer explanation

Tags

NGSS.HS-PS2-1

A person rides a bike 15 km north, then 55 km west. What is the displacement (magnitude and direction)?

Answer explanation

A sign with a mass of 312 kg is suspended between two cables that make an angle of 90.0°. If the tension in the cables are equal, calculate the tension.

Answer explanation

Tags

NGSS.HS-PS2-1

NGSS.HS-PS2-4

A child’s swing is held up by two ropes tied to a tree branch that hangs 13° from the horizontal. If the tension in each rope is 2.28 N, what is the mass of the swing?

Answer explanation

Tags

NGSS.HS-PS2-1

Perpendicular vectors are _?_