Physics- Ch. 5 Test Review

 Which of the following is a true statement regarding springs?The higher the value of the spring constant, the stiffer the spring.

• The higher the value of the spring constant, the stiffer the spring.

• In a compression spring, displacement is measured by the liberty angle.

• In Hooke's Law, the force exerted by the spring acts in the same direction as displacement.

• Springs are designed to provide unpredictable variations in force.

• The force exerted by a spring has a quadratic relationship with the displacement from equilibrium.

Answer explanation

The spring constant k is the ratio of the magnitude of the force divided by the amount of deformation. A larger k means that more force is needed to compress or stretch the spring, so the spring is stiffer.

 A net force of 320 N acts to stretch an extension spring. How far will the spring stretch if its spring constant is 1200 N/m?

• 0.13 m

• 3.8 m

• 3.8×10⁵ m

• 33 m

• 0.27 m

Answer explanation

In this case, the spring exerts a restoring force of 320 N in the negative direction. Using Hooke's Law, we find that the spring can stretch a distance of x=−F/k=−(−320 N)1200 N/m= 0.267 m.

The graph shows velocity versus time for a 10.0 kg sled pulled on a level surface by a constant horizontal force. What is the net horizontal force acting on the sled?

• 30 N

• 15 N

• 10 N

• 20 N

• 0.0 N

Answer explanation

From the graph we see that the acceleration is 1 m/s².The force isF = 10 kg × 1 m/s² = 10.0 N.

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NGSS.HS-PS2-1

A 520 kg spacecraft weighs 720 N on the surface of Planet Zphyz. What is the acceleration due to gravity on the planet’s surface?

• 2.8 m/s²

• 1.4 m/s²

• 0.0 m/s²

• 4.9 m/s²

• 0.72 m/s²

Answer explanation

720/520= 1.38

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NGSS.HS-PS2-4

A force of 210 N is applied to stretch a spring which has a spring constant of k = 1300 N/m. How much does the spring stretch past its free length?

• 2.7×10⁵ m

• 6.2 m

• 21 m

• 0.16 m

• 0.081 m

Answer explanation

−(−210) N/1300 N/m= 0.162 m.

The coefficient of kinetic friction between a floor and a box made of wood is μ_k = 0.13. How far does the box slide if it has an initial speed of v_o = 7.0 m/s?

• 21 m

• 58 m

• 77 m

• 35 m

• 19 m

Answer explanation

a_f = (9.8 m/s²)(0.13) = 1.3 m/s².

x=x+vt+1/2at² x_o = 0 m and v_o = 7 m/s.

−7 m/s/−1.3 m/s²=5.5 s.

And the distance traveled before it comes to a stop is

(7 m/s)(5.5 s) +1/2(−1.3 m/s²)(5.5 s)²= 19 m.

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NGSS.HS-PS2-1

A child sits on a tire swing that is suspended by a single rope from a tree branch. What is the tension in the rope if the mass of the child and tire is 46 kg?

• 450 N

• 2100 N

• 46 N

• 56 N

• 4.7 N

Answer explanation

The swing-and-child system is in equilibrium, so the net force must be zero. This means that the force of tension and the weight of the child must be equal. Therefore, we have T = mg = (46 kg)(9.8 N/kg) = 451 N.

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NGSS.HS-PS2-4

If a boat sails north, in what direction will the friction force be?

• east

• north

• up

• south

• down

Answer explanation

Friction alone would reduce the relative motion of the boat through the water, so it acts opposite the direction of motion.

  A net force of 48 N acts on a shopping cart full of groceries producing an acceleration of 4.0 m/s². If the empty cart has a mass of 1.0 kg, what is the total mass of the groceries inside?

• 1.0 kg

• 13 kg

• 0.083 kg

• 12 kg

• 11 kg

Answer explanation

Rearrange a = F/m to get m = F/a = 48 N / 4 m/s² = 12.0 kg. This is the total mass of the cart and groceries, so the mass of the groceries is 12.0 kg - 1 kg = 11.0 kg

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NGSS.HS-PS2-1

Jim passes a 0.93 kg basketball to his teammate by applying a net force of 72 N. What is the acceleration of the basketball while the force is being applied.

• 0.93 m/s²

• 77 m/s²

• 73 m/s²

• 67 m/s²

• 0.013 m/s²

Answer explanation

^{72 N}⁄_{0.93 kg} = 77.4 m/s².

Tags

NGSS.HS-PS2-1