Physics Midterm

Which one of the following quantities is scalar?

• force

• mass

• acceleration

• momentum

Answer explanation

mass has only a magnitude, no direction

What is the final speed of an object that starts from rest and accelerates uniformly at 4.0 meters per second² over a distance of 8.0 meters?

• 16 m/s

• 8.0 m/s

• 64 m/s

• 32 m/s

Answer explanation

Use v_f²=v_i²+2ad

Tags

NGSS.HS-PS2-1

The components of a 15-meters-per-second velocity at an angle of 60.^o above the horizontal are

• 13 m/s vertical and 7.5 m/s horizontal

• 9.0 m/s vertical and 6.0 m/s horizontal

• 7.5 m/s vertical and 13 m/s horizontal

• 6.0 m/s vertical and 9.0 m/s horizontal

Answer explanation

Vertical is 15 x sin60

Horizontal is 15 x cos60

What is the time required for an object starting from rest to fall freely 500. meters near Earth's surface?

• 7.14 s

• 25.5 s

• 51. 0 s

• 10.1 s

Answer explanation

Use d = v_it + 1/2 at²

Tags

NGSS.HS-PS2-1

A baseball bat exerts a force of magnitude F on a ball. If the mass of the bat is three times the mass of the ball, what is the magnitude of the force of the ball on the bat?

• F

• F/3

• 2F

• 3F

Answer explanation

Newton's 3rd Law

Tags

NGSS.HS-PS2-1

A 2.0-kilogram mass is located 3.0 meters above the surface of Earth. What is the magnitude of Earth's gravitational field strength at this location?

• 4.9 N/kg

• 9.8 N/kg

• 20. N/kg

• 2.0 N/kg

Answer explanation

Gravitational field strength is another way to express acceleration due to gravity. On Earth, it is 9.81 m/s² = 9.81 N/kg

Tags

NGSS.HS-PS2-4

A truck, initially traveling at a speed of 22 meters per second, increases speed at a constant rate of 2.4 meters per second² for 3.2 seconds. What is the total distance traveled by the truck during this 3.2-second time interval?

• 70. m

• 58 m

• 83 m

• 12 m

Answer explanation

Use d = v_it + 1/2 at²

Tags

NGSS.HS-PS2-1

A 15-kilogram cart is at rest on a horizontal surface. A 5-kilogram box is placed in the cart. Compared to the mass and inertia of the cart, the cartbox system has

• more mass and more inertia

• less mass and more inertia

• more mass and the same inertia

• the same mass and more inertia

Answer explanation

mass and inertia are directly related - more mass is more inertia

Tags

NGSS.HS-PS2-1

The height of a 30-story building is approximately

• 10³ m

• 10² m

• 10¹ m

• 10⁰ m

Answer explanation

Remember 1m is floor to doorknob. So 1 story is about 3 meters. 30 x 3 = 90. Closest answer is 10² = 100m

A 1.0 x 10³-kilogram car travels at a constant speed of 20. meters per second around a horizontal circular track. The diameter of the track is 1.0 x 10² meters. The magnitude of the car's centripetal acceleration is

• 4.0 m/s²

• 2.0 m/s²

• 0.20 m/s²

• 8.0 m/s²

Answer explanation

Use a_c=v²/r = (20)²/50 = 8

Tags

NGSS.HS-PS2-1